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Woodruff DC, Curtice BD, Foster JR. Seis-ing up the Super-Morrison formation sauropods. J Anat 2024. [PMID: 38978276 DOI: 10.1111/joa.14108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 06/12/2024] [Accepted: 06/20/2024] [Indexed: 07/10/2024] Open
Abstract
The Upper Jurassic Morrison Formation sauropods Diplodocus (formerly "Seismosaurus") hallorum and Supersaurus vivianae are quantifiably the largest dinosaurian taxa from the formation, as well as being among the largest dinosaurs in the world. Their extreme body size (in particular body length, c. 50+ m) has fascinated the paleontological community since their discoveries and has sparked an ongoing discussion on the trends and limits of Morrison Formation sauropod body size. Although not an undeviating proxy, often the largest and skeletally most mature specimens are among the rarest (as exemplified in Triceratops). While their body size has no phylogenetic bearing, the extreme size and potential eco and biological significance of these two sauropod taxa are frequently discussed. Whether these rare and titanically proportioned sauropod specimens are large-bodied, senescent or both is an often-repeating rhetoric. To definitively make maturational inferences about these taxa, we osteohistologically sampled the holotype of D. hallorum (NMMNH P-25079) and the second known specimen of S. vivianae (WDC DMJ-021). Our age-determinant and maturational assessments indicate that both specimens were skeletally mature at their respective age of death. Retrocalculation methods for D. hallorum NMMNH P-25079 produce a maximum age-at-death estimation of 60 years, whereas S. vivianae WDC DMJ-021 lived well past skeletal maturity-so much so that reliable retrocalculated ages cannot be accurately determined at this time. Additionally, the rarity of such large sauropods within the Morrison Formation might be more parsimoniously explained as relating to their maturity as opposed to representing aberrant taxa on the Morrison landscape.
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Affiliation(s)
- D Cary Woodruff
- Phillip and Patricia Frost Museum of Science, Miami, Florida, USA
- Museum of the Rockies, Bozeman, Montana, USA
| | | | - John R Foster
- Utah Field House of Natural History State Park Museum, Vernal, Utah, USA
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2
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von Baczko MB, Zariwala J, Ballentine SE, Desojo JB, Hutchinson JR. Biomechanical modeling of musculoskeletal function related to the terrestrial locomotion of Riojasuchus tenuisceps (Archosauria: Ornithosuchidae). Anat Rec (Hoboken) 2024. [PMID: 38943347 DOI: 10.1002/ar.25528] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/30/2024] [Accepted: 06/11/2024] [Indexed: 07/01/2024]
Abstract
Riojasuchus tenuisceps was a pseudosuchian archosaur from the Late Triassic period in Argentina. Like other ornithosuchids, it had unusual morphology such as a unique "crocodile-reversed" ankle joint, a lesser trochanter as in dinosaurs and a few other archosaurs, robust vertebrae, and somewhat shortened, gracile forelimbs. Such traits have fuelled controversies about its locomotor function-were its limbs erect or "semi-erect"? Was it quadrupedal or bipedal, or a mixture thereof? These controversies seem to persist because analyses have been qualitative (functional morphology) or correlative (morphometrics) rather than explicitly, quantitatively testing mechanistic hypotheses about locomotor function. Here, we develop a 3D whole-body model of R. tenuisceps with the musculoskeletal apparatus of the hindlimbs represented in detail using a new muscle reconstruction. We use this model to quantify the body dimensions and hindlimb muscle leverages of this enigmatic taxon, and to estimate joint ranges of motion and qualitative joint functions. Our model supports prior arguments that R. tenuisceps used an erect posture, parasagittal gait and plantigrade pes. However, some of our inferences illuminate the rather contradictory nature of evidence from the musculoskeletal system of R. tenuisceps-different features support (or are ambiguous regarding) quadrupedalism or bipedalism. Deeper analyses of our biomechanical model could move toward a consensus regarding ornithosuchid locomotion. Answering these questions would not only help understand the palaeobiology and bizarre morphology of this clade, but also more broadly if (or how) locomotor abilities played a role in the survival versus extinction of various archosaur lineages during the end-Triassic mass extinction event.
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Affiliation(s)
- M Belen von Baczko
- Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales Bernardino Rivadavia, Ciudad Autónoma de Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Juned Zariwala
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK
- School of Life and Environmental Sciences, College of Health and Sciences, University of Lincoln, Brayford Pool Campus, Lincoln, UK
| | - Sarah Elizabeth Ballentine
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK
| | - Julia B Desojo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
- División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, La Plata, Argentina
| | - John R Hutchinson
- Structure & Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, Hertfordshire, UK
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3
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Han F, Yu Y, Zhang S, Zeng R, Wang X, Cai H, Wu T, Wen Y, Cai S, Li C, Wu R, Zhao Q, Xu X. Exceptional Early Jurassic fossils with leathery eggs shed light on dinosaur reproductive biology. Natl Sci Rev 2024; 11:nwad258. [PMID: 38707200 PMCID: PMC11067957 DOI: 10.1093/nsr/nwad258] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/25/2023] [Accepted: 09/27/2023] [Indexed: 05/07/2024] Open
Abstract
Our understanding of pre-Cretaceous dinosaur reproduction is hindered by a scarcity of evidence within fossil records. Here we report three adult skeletons and five clutches of embryo-containing eggs of a new sauropodomorph from the Lower Jurassic of southwestern China, displaying several significant reproductive features that are either unknown or unlike other early-diverging sauropodomorphs, such as relatively large eggs with a relatively thick calcareous shell formed by prominent mammillary cones, synchronous hatching and a transitional prehatching posture between the crocodilians and living birds. Most significantly, these Early Jurassic fossils provide strong evidence for the earliest known leathery eggs. Our comprehensive quantitative analyses demonstrate that the first dinosaur eggs were probably leathery, elliptical and relatively small, but with relatively long eggshell units, and that along the line to living birds, the most significant change in reptilian egg morphology occurred early in theropod evolution rather than near the origin of Aves.
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Affiliation(s)
- Fenglu Han
- School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan 430074, China
| | - Yilun Yu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Shukang Zhang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Rong Zeng
- Guizhou Provincial Museum, Guiyang 550081, China
| | - Xinjin Wang
- Guizhou Provincial Institute of Cultural Relics and Archaeology, Guiyang 550001, China
| | - Huiyang Cai
- Guizhou Provincial Museum, Guiyang 550081, China
| | | | - Yingfeng Wen
- Pingba Institute of Cultural Relics Administration, Anshun 550820, China
| | - Sifu Cai
- Guizhou Provincial Museum, Guiyang 550081, China
| | - Chun Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Rui Wu
- School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan 430074, China
| | - Qi Zhao
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
| | - Xing Xu
- Centre for Vertebrate Evolutionary Biology, Yunnan University, Kunming 650091, China
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China
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4
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Müller RT, Garcia MS, Bem FP, Damke LVS, Fonseca AO, Da-Rosa ÁAS. On a skeletally immature individual of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the upper Triassic of southern Brazil. Anat Rec (Hoboken) 2024; 307:1071-1083. [PMID: 37409690 DOI: 10.1002/ar.25285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Revised: 06/21/2023] [Accepted: 06/26/2023] [Indexed: 07/07/2023]
Abstract
The lineage of sauropodomorph dinosaurs raised some of the most impressive animals that ever walked on Earth. However, the massive titans of the Mesozoic Era originated from far smaller dinosaurs. The Triassic beds from Brazil yielded the earliest part of this evolutionary history. Despite the diverse fossil record of early sauropodomorphs, juvenile specimens, as well as certain species are poorly sampled. This is the case for Unaysaurus tolentinoi, an unaysaurid sauropodomorph from Caturrita Formation (ca. 225 Ma; early Norian, Late Triassic). The holotype and only specimen of U. tolentinoi was excavated from the Água Negra Locality (São Martinho da Serra, Rio Grande do Sul, Brazil) in 1998. More than two decades later, no other fossil vertebrates have been reported from the same fossiliferous site. Here we describe a skeletally immature specimen which was found in association with the holotype of U. tolentinoi. The specimen was discovered after a first-hand examination of the holotype and comprises some isolated vertebrae and elements from the posterior autopodium. According to linear regressions, its metatarsal I is approximately 41.7 mm in length, compared to approximately 75.9 mm in the holotype. The repeated elements and reduced size indicates that it does not belong to the elements originally used to erect U. tolentinoi. Rather, the specimen is assigned to U. tolentinoi by topotypy and shared morphology. In addition to the reduced size, distinct lines of evidence (e.g., neurocentral sutures; bone texture) support its assignment to a skeletally immature individual. In sum, the new material expands the record of U. tolentinoi, and represents an additional juvenile dinosaur from the Caturrita Formation.
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Affiliation(s)
- Rodrigo T Müller
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Maurício S Garcia
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Fabiula P Bem
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Lísie V S Damke
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - André O Fonseca
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Átila A S Da-Rosa
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
- Laboratório de Estratigrafia e Paleobiologia, Universidade Federal de Santa Maria, Santa Maria, Brazil
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5
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Dos Santos DM, de Carvalho JC, de Oliveira CEM, de Andrade MB, Santucci RM. Cranial and postcranial anatomy of a juvenile baurusuchid (Notosuchia, Crocodylomorpha) and the taxonomical implications of ontogeny. Anat Rec (Hoboken) 2024. [PMID: 38429867 DOI: 10.1002/ar.25419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 03/03/2024]
Abstract
Baurusuchidae comprises a clade of top-tier terrestrial predators and are among the most abundant crocodyliforms found in the Adamantina Formation, Bauru Basin, Brazil (Campanian-Maastrichtian). Here, we provide a detailed description of the cranial and postcranial osteology and myology of the most complete juvenile baurusuchid found to date. Although the preservation of juvenile individuals is somewhat rare, previously reported occurrences of baurusuchid egg clutches, a yearling individual, and larger, but skeletally immature specimens, comprise a unique opportunity to track anatomical changes throughout their ontogenetic series. Its cranial anatomy was resolved with the aid of a three-dimensional model generated by the acquisition of computed tomography data, and its inferred adductor mandibular musculature was compared to that of mature specimens in order to assess possible ontogenetic shifts. A subsequent phylogenetic analysis included the scoring of Gondwanasuchus scabrosus, the smallest baurusuchid species known to date, to evaluate its phylogenetic relations relative to a known juvenile. We find considerable differences between juveniles and adults concerning skull ornamentation and muscle development, which might indicate ontogenetic niche partitioning, and also anatomical and phylogenetic evidence that G. scabrosus corresponds to a young semaphoront lacking mature cranial features.
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Affiliation(s)
- Daniel Martins Dos Santos
- Zoology Graduate Program, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
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6
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Anderson L, Brassey C, Pond S, Bates K, Sellers WI. Investigating the quadrupedal abilities of Scutellosaurus lawleri and its implications for locomotor behavior evolution among dinosaurs. Anat Rec (Hoboken) 2023; 306:2514-2536. [PMID: 36896818 DOI: 10.1002/ar.25189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 03/11/2023]
Abstract
A reversion to secondary quadrupedality is exceptionally rare in nature, yet the convergent re-evolution of this locomotor style occurred at least four separate times within Dinosauria. Facultative quadrupedality, an intermediate state between obligate bipedality and obligate quadrupedality, may have been an important transitional step in this locomotor shift, and is proposed for a range of basal ornithischians and sauropodomorphs. Advances in virtual biomechanical modeling and simulation have allowed for the investigation of limb anatomy and function in a range of extinct dinosaurian species, yet this technique has not been widely applied to explore facultatively quadrupedal gait generation. This study places its focus on Scutellosaurus, a basal thyreophoran that has previously been described as both an obligate biped and a facultative quadruped. The functional anatomy of the musculoskeletal system (myology, mass properties, and joint ranges of motion) has been reconstructed using extant phylogenetic bracketing and comparative anatomical datasets. This information was used to create a multi-body dynamic locomotor simulation that demonstrates that whil quadrupedal gaits were physically possible, they did not outperform bipedal gaits is any tested metric. Scutellosaurus cannot therefore be described as an obligate biped, but we would predict its use of quadrupedality would be very rare, and perhaps restricted to specific activities such as foraging. This finding suggests that basal thyreophorans are still overwhelmingly bipedal but is perhaps indicative of an adaptive pathway for later evolution of quadrupedality.
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7
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Demuth OE, Wiseman ALA, Hutchinson JR. Quantitative biomechanical assessment of locomotor capabilities of the stem archosaur Euparkeria capensis. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221195. [PMID: 36704253 PMCID: PMC9874271 DOI: 10.1098/rsos.221195] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 01/10/2023] [Indexed: 06/18/2023]
Abstract
Birds and crocodylians are the only remaining members of Archosauria (ruling reptiles) and they exhibit major differences in posture and gait, which are polar opposites in terms of locomotor strategies. Their broader lineages (Avemetatarsalia and Pseudosuchia) evolved a multitude of locomotor modes in the Triassic and Jurassic periods, including several occurrences of bipedalism. The exact timings and frequencies of bipedal origins within archosaurs, and thus their ancestral capabilities, are contentious. It is often suggested that archosaurs ancestrally exhibited some form of bipedalism. Euparkeria capensis is a central taxon for the investigation of locomotion in archosaurs due to its phylogenetic position and intermediate skeletal morphology, and is argued to be representative of facultative bipedalism in this group. However, no studies to date have biomechanically tested if bipedality was feasible in Eupakeria. Here, we use musculoskeletal models and static simulations in its hindlimb to test the influences of body posture and muscle parameter estimation methods on locomotor potential. Our analyses show that the resulting negative pitching moments around the centre of mass were prohibitive to sustainable bipedality. We conclude that it is unlikely that Euparkeria was facultatively bipedal, and was probably quadrupedal, rendering the inference of ancestral bipedal abilities in Archosauria unlikely.
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Affiliation(s)
- Oliver E. Demuth
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, UK
- Department of Earth Sciences, University of Cambridge, Cambridge, UK
| | - Ashleigh L. A. Wiseman
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, UK
- McDonald Institute for Archaeological Research, University of Cambridge, Cambridge, UK
| | - John R. Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College, Hatfield, UK
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8
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Cuff AR, Demuth OE, Michel K, Otero A, Pintore R, Polet DT, Wiseman ALA, Hutchinson JR. Walking-and Running and Jumping-with Dinosaurs and Their Cousins, Viewed Through the Lens of Evolutionary Biomechanics. Integr Comp Biol 2022; 62:icac049. [PMID: 35595475 DOI: 10.1093/icb/icac049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Archosauria diversified throughout the Triassic Period before experiencing two mass extinctions near its end ∼201 Mya, leaving only the crocodile-lineage (Crocodylomorpha) and bird-lineage (Dinosauria) as survivors; along with the pterosaurian flying reptiles. About 50 years ago, the "locomotor superiority hypothesis" (LSH) proposed that dinosaurs ultimately dominated by the Early Jurassic Period because their locomotion was superior to other archosaurs'. This idea has been debated continuously since, with taxonomic and morphological analyses suggesting dinosaurs were "lucky" rather than surviving due to being biologically superior. However, the LSH has never been tested biomechanically. Here we present integration of experimental data from locomotion in extant archosaurs with inverse and predictive simulations of the same behaviours using musculoskeletal models, showing that we can reliably predict how extant archosaurs walk, run and jump. These simulations have been guiding predictive simulations of extinct archosaurs to estimate how they moved, and we show our progress in that endeavour. The musculoskeletal models used in these simulations can also be used for simpler analyses of form and function such as muscle moment arms, which inform us about more basic biomechanical similarities and differences between archosaurs. Placing all these data into an evolutionary and biomechanical context, we take a fresh look at the LSH as part of a critical review of competing hypotheses for why dinosaurs (and a few other archosaur clades) survived the Late Triassic extinctions. Early dinosaurs had some quantifiable differences in locomotor function and performance vs. some other archosaurs, but other derived dinosaurian features (e.g., metabolic or growth rates, ventilatory abilities) are not necessarily mutually exclusive from the LSH; or maybe even an opportunistic replacement hypothesis; in explaining dinosaurs' success.
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Affiliation(s)
- A R Cuff
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Human Anatomy Resource Centre, University of Liverpool, Liverpool, United Kingdom
| | - O E Demuth
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Department of Earth Sciences, University of Cambridge, United Kingdom
| | - K Michel
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
| | - A Otero
- CONICET - División Paleontología de Vertebrados, Facultad de Ciencias Naturales y Museo, Anexo Laboratorios, La Plata, Argentina
| | - R Pintore
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- Mécanismes adaptatifs et évolution (MECADEV) / UMR 7179, CNRS / Muséum National d'Histoire Naturelle, France
| | - D T Polet
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
| | - A L A Wiseman
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
- McDonald Institute for Archaeological Research, University of Cambridge, United Kingdom
| | - J R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, United Kingdom
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9
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Cordero GA, Vamberger M, Fritz U, Ihlow F. Skeletal repatterning enhances the protective capacity of the shell in African hinge-back tortoises (Kinixys). Anat Rec (Hoboken) 2022; 306:1558-1573. [PMID: 35582737 DOI: 10.1002/ar.24954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 04/03/2022] [Accepted: 04/20/2022] [Indexed: 11/06/2022]
Abstract
Changes in the structural association of skeletal traits are crucial to the evolution of novel forms and functions. In vertebrates, such rearrangements often occur gradually and may precede or coincide with the functional activation of skeletal traits. To illustrate this process, we examined the ontogeny of African hinge-back tortoises (Kinixys spp.). Kinixys species feature a moveable "hinge" on the dorsal shell (carapace) that enables shell closure (kinesis) when the hind limbs are withdrawn. This hinge, however, is absent in juveniles. Herein, we describe how this unusual phenotype arises via alterations in the tissue configuration and shape of the carapace. The ontogenetic repatterning of osseous and keratinous tissue coincided with shifts in morphological integration and the establishment of anterior (static) and posterior (kinetic) carapacial modules. Based on ex vivo skeletal movement and raw anatomy, we propose that Kinixys employs a "sliding hinge" shell-closing system that overcomes thoracic rigidity and enhances the protective capacity of the carapace. Universal properties of the vertebrate skeleton, such as plasticity, modularity, and secondary maturation processes, contributed to adaptive evolutionary change in Kinixys. We discuss a hypothetical model to explain the delayed emergence of skeletal traits and its relevance to the origins of novel form-to-function relationships.
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Affiliation(s)
- Gerardo A Cordero
- Department of Geosciences, University of Tübingen, Tübingen, Germany
| | | | - Uwe Fritz
- Museum of Zoology, Senckenberg Dresden, Dresden, Germany
| | - Flora Ihlow
- Museum of Zoology, Senckenberg Dresden, Dresden, Germany
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10
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Prondvai E, Kocsis AT, Abourachid A, Adriaens D, Godefroit P, Hu DY, Butler RJ. Radial porosity profiles: a new bone histological method for comparative developmental analysis of diametric limb bone growth. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211893. [PMID: 35582660 PMCID: PMC9091851 DOI: 10.1098/rsos.211893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
In fossil tetrapods, limb bone histology is considered the most reliable tool not only for inferring skeletal maturity-a crucial assessment in palaeobiological and evolutionary studies-but also for evaluating the growth dynamics within the ontogenetic window represented by the primary bone cortex. Due to its complex relationship with bone growth and functional maturation, primary cortical vascularity is an indispensable osteohistological character for reconstructing growth dynamics, especially in the context of various developmental strategies along the precocial-altricial spectrum. Using this concept as our working hypothesis, we developed a new quantitative osteohistological parameter, radial porosity profile (RPP), that captures relative cortical porosity changes in limb bones as trajectories. We built a proof-of-concept RPP dataset on extant birds, then added fossil paravian dinosaurs and performed a set of trajectory-grouping analyses to identify potential RPP categories and evaluate them in the context of our ontogeny-developmental strategy working hypothesis. We found that RPPs, indeed, reflect important developmental features within and across elements, specimens and taxa, supporting their analytical power. Our RPPs also revealed unexpected potential osteohistological correlates of growth and functional development of limb bones. The diverse potential applications of RPPs open up new research directions in the evolution of locomotor ontogeny.
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Affiliation(s)
- Edina Prondvai
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
- MTA-MTM-ELTE Research Group for Paleontology, Budapest, Hungary
| | - Adam T. Kocsis
- Department of Palaeobiology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Anick Abourachid
- Département Adaptations du Vivant, UMR 7179 Muséum National d'Histoire Naturelle – CNRS, Paris, France
| | - Dominique Adriaens
- Department of Biology, Evolutionary Morphology of Vertebrates, Ghent University, Ghent, Belgium
| | - Pascal Godefroit
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
| | - Dong-Yu Hu
- Key Laboratory for Evolution of Past Life in Northeast Asia, Ministry of Land and Resources, Paleontological Institute of Shenyang Normal University, Shenyang, People's Republic of China
- Paleontological Museum of Liaoning, Shenyang, People's Republic of China
| | - Richard J. Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK
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11
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Lefebvre R, Houssaye A, Mallison H, Cornette R, Allain R. A path to gigantism: Three‐dimensional study of the sauropodomorph limb long bone shape variation in the context of the emergence of the sauropod bauplan. J Anat 2022; 241:297-336. [PMID: 35249216 PMCID: PMC9296025 DOI: 10.1111/joa.13646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 02/09/2022] [Accepted: 02/15/2022] [Indexed: 11/30/2022] Open
Abstract
Sauropodomorph dinosaurs include the largest terrestrial animals that ever lived on Earth. The early representatives of this clade were, however, relatively small and partially to totally bipedal, conversely to the gigantic and quadrupedal sauropods. Although the sauropod bauplan is well defined, notably by the acquisition of columnar limbs, the evolutionary sequence leading to its emergence remains debated. Here, we aim to tackle this evolutionary episode by investigating shape variation in the six limb long bones for the first time using three‐dimensional geometric morphometrics. The morphological features of the forelimb zeugopod bones related to the sauropod bauplan tend to appear abruptly, whereas the pattern is more gradual for the hindlimb zeugopod bones. The stylopod bones tend to show the same pattern as their respective zeugopods. The abrupt emergence of the sauropod forelimb questions the locomotor abilities of non‐sauropodan sauropodomorphs inferred as quadrupeds. Features characterizing sauropods tend to corroborate a view of their locomotion mainly based on stylopod retraction. An allometric investigation of the shape variation in accordance with size highlight differences in hindlimb bone allometries between the sauropods and the non‐sauropodan sauropodomorphs. These differences notably correspond to an unexpected robustness decrease trend in the sauropod hindlimb zeugopod. In addition to forelimb bones that appear to be proportionally more gracile than in non‐sauropodan sauropodomorphs, sauropods may have relied on limb architecture and features related to the size increase, rather than general robustness, to deal with the role of weight‐bearing.
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Affiliation(s)
- Rémi Lefebvre
- Mécanismes Adaptatifs et Évolution, UMR 7179, MNHN, CNRS Muséum National d'Histoire Naturelle Paris France
| | - Alexandra Houssaye
- Mécanismes Adaptatifs et Évolution, UMR 7179, MNHN, CNRS Muséum National d'Histoire Naturelle Paris France
| | | | - Raphaël Cornette
- Institut de Systématique, Évolution, Biodiversité, UMR7205, MNHN, CNRS, SU, EPHE, UA Muséum National d'Histoire Naturelle Paris France
| | - Ronan Allain
- Centre de Recherche en Paléontologie – Paris, UMR 7207, MNHN, CNRS, SU Muséum National d'Histoire Naturelle Paris France
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12
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Ballell A, Rayfield EJ, Benton MJ. Walking with early dinosaurs: appendicular myology of the Late Triassic sauropodomorph Thecodontosaurus antiquus. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211356. [PMID: 35116154 PMCID: PMC8767213 DOI: 10.1098/rsos.211356] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 12/06/2021] [Indexed: 06/14/2023]
Abstract
Dinosaur evolution is marked by numerous independent shifts from bipedality to quadrupedality. Sauropodomorpha is one of the lineages that transitioned from small bipedal forms to graviportal quadrupeds, with an array of intermediate postural strategies evolving in non-sauropodan sauropodomorphs. This locomotor shift is reflected by multiple modifications of the appendicular skeleton, coupled with a drastic rearrangement of the limb musculature. Here, we describe the osteological correlates of appendicular muscle attachment of the Late Triassic sauropodomorph Thecodontosaurus antiquus from multiple well-preserved specimens and provide the first complete forelimb and hindlimb musculature reconstruction of an early-branching sauropodomorph. Comparisons with other sauropodomorphs and early dinosaurs reveal a unique combination of both plesiomorphic and derived musculoskeletal features. The diversity of appendicular osteological correlates among early dinosaurs and their relevance in muscle reconstruction are discussed. In line with previous evidence, aspects of the limb muscle arrangement, such as conspicuous correlates of lower limb extensors and flexors and low moment arms of hip extensors and flexors, suggest Thecodontosaurus was an agile biped. This reconstruction helps to elucidate the timing of important modifications of the appendicular musculature in the evolution of sauropodomorphs which facilitated the transition to quadrupedalism and contributed to their evolutionary success.
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Affiliation(s)
- Antonio Ballell
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Emily J. Rayfield
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Michael J. Benton
- School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK
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13
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Pintore R, Houssaye A, Nesbitt SJ, Hutchinson JR. Femoral specializations to locomotor habits in early archosauriforms. J Anat 2021; 240:867-892. [PMID: 34841511 PMCID: PMC9005686 DOI: 10.1111/joa.13598] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 10/27/2021] [Accepted: 11/15/2021] [Indexed: 12/14/2022] Open
Abstract
The evolutionary history of archosaurs and their closest relatives is characterized by a wide diversity of locomotor modes, which has even been suggested as a pivotal aspect underlying the evolutionary success of dinosaurs vs. pseudosuchians across the Triassic–Jurassic transition. This locomotor diversity (e.g., more sprawling/erect; crouched/upright; quadrupedal/bipedal) led to several morphofunctional specializations of archosauriform limb bones that have been studied qualitatively as well as quantitatively through various linear morphometric studies. However, differences in locomotor habits have never been studied across the Triassic–Jurassic transition using 3D geometric morphometrics, which can relate how morphological features vary according to biological factors such as locomotor habit and body mass. Herein, we investigate morphological variation across a dataset of 72 femora from 36 different species of archosauriforms. First, we identify femoral head rotation, distal slope of the fourth trochanter, femoral curvature, and the angle between the lateral condyle and crista tibiofibularis as the main features varying between bipedal and quadrupedal taxa, all of these traits having a stronger locomotor signal than the lesser trochanter's proximal extent. We show a significant association between locomotor mode and phylogeny, but with the locomotor signal being stronger than the phylogenetic signal. This enables us to predict locomotor modes of some of the more ambiguous early archosauriforms without relying on the relationships between hindlimb and forelimb linear bone dimensions as in prior studies. Second, we highlight that the most important morphological variation is linked to the increase of body size, which impacts the width of the epiphyses and the roundness and proximodistal position of the fourth trochanter. Furthermore, we show that bipedal and quadrupedal archosauriforms have different allometric trajectories along the morphological variation in relation to body size. Finally, we demonstrate a covariation between locomotor mode and body size, with variations in femoral bowing (anteroposterior curvature) being more distinct among robust femora than gracile ones. We also identify a decoupling in fourth trochanter variation between locomotor mode (symmetrical to semi‐pendant) and body size (sharp to rounded). Our results indicate a similar level of morphological disparity linked to a clear convergence in femoral robusticity between the two clades of archosauriforms (Pseudosuchia and Avemetatarsalia), emphasizing the importance of accounting for body size when studying their evolutionary history, as well as when studying the functional morphology of appendicular features. Determining how early archosauriform skeletal features were impacted by locomotor habits and body size also enables us to discuss the potential homoplasy of some phylogenetic characters used previously in cladistic analyses as well as when bipedalism evolved in the avemetatarsalian lineage. This study illuminates how the evolution of femoral morphology in early archosauriforms was functionally constrained by locomotor habit and body size, which should aid ongoing discussions about the early evolution of dinosaurs and the nature of their evolutionary “success” over pseudosuchians.
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Affiliation(s)
- Romain Pintore
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, UK.,Mécanismes adaptatifs et évolution (MECADEV)/UMR 7179, CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Alexandra Houssaye
- Mécanismes adaptatifs et évolution (MECADEV)/UMR 7179, CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | | | - John R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, Hatfield, UK
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14
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Earliest evidence of herd-living and age segregation amongst dinosaurs. Sci Rep 2021; 11:20023. [PMID: 34675327 PMCID: PMC8531321 DOI: 10.1038/s41598-021-99176-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 09/21/2021] [Indexed: 02/08/2023] Open
Abstract
Sauropodomorph dinosaurs dominated the herbivorous niches during the first 40 million years of dinosaur history (Late Triassic-Early Jurassic), yet palaeobiological factors that influenced their evolutionary success are not fully understood. For instance, knowledge on their behaviour is limited, although herding in sauropodomorphs has been well documented in derived sauropods from the Late Jurassic and Cretaceous. Here we report an exceptional fossil occurrence from Patagonia that includes over 100 eggs and skeletal specimens of 80 individuals of the early sauropodomorph Mussaurus patagonicus, ranging from embryos to fully-grown adults, with an Early Jurassic age as determined by high-precision U-Pb zircon geochronology. Most specimens were found in a restricted area and stratigraphic interval, with some articulated skeletons grouped in clusters of individuals of approximately the same age. Our new discoveries indicate the presence of social cohesion throughout life and age-segregation within a herd structure, in addition to colonial nesting behaviour. These findings provide the earliest evidence of complex social behaviour in Dinosauria, predating previous records by at least 40 My. The presence of sociality in different sauropodomorph lineages suggests a possible Triassic origin of this behaviour, which may have influenced their early success as large terrestrial herbivores.
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15
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Chapelle KEJ, Botha J, Choiniere JN. Extreme growth plasticity in the early branching sauropodomorph Massospondylus carinatus. Biol Lett 2021; 17:20200843. [PMID: 33975484 DOI: 10.1098/rsbl.2020.0843] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
There is growing evidence of developmental plasticity in early branching dinosaurs and their outgroups. This is reflected in disparate patterns of morphological and histological change during ontogeny. In fossils, only the osteohistological assessment of annual lines of arrested growth (LAGs) can reveal the pace of skeletal growth. Some later branching non-bird dinosaur species appear to have followed an asymptotic growth pattern, with declining growth rates at increasing ontogenetic ages. By contrast, the early branching sauropodomorph Plateosaurus trossingensis appears to have had plastic growth, suggesting that this was the plesiomorphic condition for dinosaurs. The South African sauropodomorph Massospondylus carinatus is an ideal taxon in which to test this because it is known from a comprehensive ontogenetic series, it has recently been stratigraphically and taxonomically revised, and it lived at a time of ecosystem upheaval following the end-Triassic extinction. Here, we report on the results of a femoral osteohistological study of M. carinatus comprising 20 individuals ranging from embryo to skeletally mature. We find major variability in the spacing of the LAGs and infer disparate body masses for M. carinatus individuals at given ontogenetic ages, contradicting previous studies. These findings are consistent with a high degree of growth plasticity in M. carinatus.
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Affiliation(s)
- Kimberley E J Chapelle
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, 2050 South Africa.,School of Geosciences, University of the Witwatersrand, Johannesburg, 2050 South Africa
| | - Jennifer Botha
- Karoo Palaeontology Department, National Museum, Bloemfontein, 9300 South Africa.,Department of Zoology and Entomology, University of the Free State, Bloemfontein, 9300 South Africa
| | - Jonah N Choiniere
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, 2050 South Africa
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16
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Fabbri M, Navalón G, Mongiardino Koch N, Hanson M, Petermann H, Bhullar BA. A shift in ontogenetic timing produced the unique sauropod skull. Evolution 2021; 75:819-831. [PMID: 33578446 DOI: 10.1111/evo.14190] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 01/30/2021] [Indexed: 11/29/2022]
Abstract
Sauropod dinosaurs include the largest terrestrial vertebrates that have ever lived. Virtually every part of the sauropod body is heavily modified in association with gigantic size and associated physiological alterations. Sauropod skulls are no exception: they feature elongated, telescoped facial regions connected to tilted neurocrania and reoriented jaw adductor muscles. Several of these cranial features have been suggested to be adaptations for feeding on the one hand and the result of paedomorphic transformation near the base of Sauropoda on the other. However, the scarcity of sauropodomorph ontogenetic series has impeded further investigation of these hypotheses. We re-evaluated the cranial material attributed to the early sauropodomorph Anchisaurus, which our phylogenetic analyses confirm to be closely related to sauropods. Digital assembly of μCT-scanned skulls of the two known specimens, a juvenile and an adult, permitted us to examine the detailed ontogeny of cranial elements. The skull anatomy of Anchisaurus is distinguished by a mosaic of ancestral saurischian and sauropod-like characters. Sauropod-like characters of the braincase and adductor chamber appear late in ontogeny, suggesting that these features first evolved by the developmental mechanism of terminal addition. Shape analyses and investigation of allometric evolution demonstrate that cranial characters that appear late in the ontogeny of sauropodomorphs closely related to sauropods are already present in the embryos and juveniles of sauropods, suggesting a predisplacement-type shift in developmental timing from the ancestral anchisaurian condition. We propose that this developmental shift relaxed prior constraints on skull morphology, allowing sauropods to explore a novel range of phenotypes and enabling specializations of the feeding apparatus. The shift in timing occurred in concert with the evolution of gigantism and physiological and locomotory innovations.
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Affiliation(s)
- Matteo Fabbri
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, 06511.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, 06511
| | - Guillermo Navalón
- Department of Earth Sciences, University of Oxford, Oxford, OX1 3AN, United Kingdom.,Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, Madrid, 28049, Spain
| | - Nicolás Mongiardino Koch
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, 06511.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, 06511
| | - Michael Hanson
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, 06511.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, 06511
| | - Holger Petermann
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, 06511.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, 06511.,Denver Museum of Nature and Science, Denver, Colorado, 80205
| | - Bhart-Anjan Bhullar
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, 06511.,Peabody Museum of Natural History, Yale University, New Haven, Connecticut, 06511
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17
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Ballell A, King JL, Neenan JM, Rayfield EJ, Benton MJ. The braincase, brain and palaeobiology of the basal sauropodomorph dinosaur Thecodontosaurus antiquus. Zool J Linn Soc 2020. [DOI: 10.1093/zoolinnean/zlaa157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
Sauropodomorph dinosaurs underwent drastic changes in their anatomy and ecology throughout their evolution. The Late Triassic Thecodontosaurus antiquus occupies a basal position within Sauropodomorpha, being a key taxon for documenting how those morphofunctional transitions occurred. Here, we redescribe the braincase osteology and reconstruct the neuroanatomy of Thecodontosaurus, based on computed tomography data. The braincase of Thecodontosaurus shares the presence of medial basioccipital components of the basal tubera and a U-shaped basioccipital–parabasisphenoid suture with other basal sauropodomorphs and shows a distinct combination of characters: a straight outline of the braincase floor, an undivided metotic foramen, an unossified gap, large floccular fossae, basipterygoid processes perpendicular to the cultriform process in lateral view and a rhomboid foramen magnum. We reinterpret these braincase features in the light of new discoveries in dinosaur anatomy. Our endocranial reconstruction reveals important aspects of the palaeobiology of Thecodontosaurus, supporting a bipedal stance and cursorial habits, with adaptations to retain a steady head and gaze while moving. We also estimate its hearing frequency and range based on endosseous labyrinth morphology. Our study provides new information on the pattern of braincase and endocranial evolution in Sauropodomorpha.
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Affiliation(s)
- Antonio Ballell
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - J Logan King
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - James M Neenan
- Oxford University Museum of Natural History, Parks Road, Oxford, UK
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18
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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19
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Müller RT, Ferreira JD, Pretto FA, Bronzati M, Kerber L. The endocranial anatomy of Buriolestes schultzi (Dinosauria: Saurischia) and the early evolution of brain tissues in sauropodomorph dinosaurs. J Anat 2020; 238:809-827. [PMID: 33137855 DOI: 10.1111/joa.13350] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 10/05/2020] [Accepted: 10/09/2020] [Indexed: 12/26/2022] Open
Abstract
Our knowledge on the anatomy of the first dinosaurs (Late Triassic, 235-205 Ma) has drastically increased in the last years, mainly due to several new findings of exceptionally well-preserved specimens. Nevertheless, some structures such as the neurocranium and its associated structures (brain, labyrinth, cranial nerves, and vasculature) remain poorly known, especially due to the lack of specimens preserving a complete and articulated neurocranium. This study helps to fill this gap by investigating the endocranial cavity of one of the earliest sauropodomorphs, Buriolestes schultzi, from the Upper Triassic (Carnian-c. 233 Ma) of Brazil. The endocranial anatomy of this animal sheds light on the ancestral condition of the brain of sauropodomorphs, revealing an elongated olfactory tract combined to a relatively small pituitary gland and well-developed flocculus of the cerebellum. These traits change drastically across the evolutionary history of sauropodomorphs, reaching the opposite morphology in Jurassic times. Furthermore, we present here the first calculations of the Reptile Encephalization Quotient (REQ) for a Triassic dinosaur. The REQ of B. schultzi is lower than that of Jurassic theropods, but higher than that of later sauropodomorphs. The combination of cerebral, dental, and postcranial data suggest that B. schultzi was an active small predator, able to track moving prey.
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Affiliation(s)
- Rodrigo T Müller
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, Brazil
| | - José D Ferreira
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Flávio A Pretto
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, Brazil.,Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Mario Bronzati
- Laboratório de Evolução e Biologia Integrativa, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil
| | - Leonardo Kerber
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria, São João do Polêsine, Brazil.,Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil.,Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, Belém, Brazil
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20
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Campione NE, Evans DC. The accuracy and precision of body mass estimation in non-avian dinosaurs. Biol Rev Camb Philos Soc 2020; 95:1759-1797. [PMID: 32869488 DOI: 10.1111/brv.12638] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/20/2022]
Abstract
Inferring the body mass of fossil taxa, such as non-avian dinosaurs, provides a powerful tool for interpreting physiological and ecological properties, as well as the ability to study these traits through deep time and within a macroevolutionary context. As a result, over the past 100 years a number of studies advanced methods for estimating mass in dinosaurs and other extinct taxa. These methods can be categorized into two major approaches: volumetric-density (VD) and extant-scaling (ES). The former receives the most attention in non-avian dinosaurs and advanced appreciably over the last century: from initial physical scale models to three-dimensional (3D) virtual techniques that utilize scanned data obtained from entire skeletons. The ES approach is most commonly applied to extinct members of crown clades but some equations are proposed and utilized in non-avian dinosaurs. Because both approaches share a common goal, they are often viewed in opposition to one another. However, current palaeobiological research problems are often approach specific and, therefore, the decision to utilize a VD or ES approach is largely question dependent. In general, biomechanical and physiological studies benefit from the full-body reconstruction provided through a VD approach, whereas large-scale evolutionary and ecological studies require the extensive data sets afforded by an ES approach. This study summarizes both approaches to body mass estimation in stem-group taxa, specifically non-avian dinosaurs, and provides a comparative quantitative framework to reciprocally illuminate and corroborate VD and ES approaches. The results indicate that mass estimates are largely consistent between approaches: 73% of VD reconstructions occur within the expected 95% prediction intervals of the ES relationship. However, almost three quarters of outliers occur below the lower 95% prediction interval, indicating that VD mass estimates are, on average, lower than would be expected given their stylopodial circumferences. Inconsistencies (high residual and per cent prediction deviation values) are recovered to a varying degree among all major dinosaurian clades along with an overall tendency for larger deviations between approaches among small-bodied taxa. Nonetheless, our results indicate a strong corroboration between recent iterations of the VD approach based on 3D specimen scans suggesting that our current understanding of size in dinosaurs, and hence its biological correlates, has improved over time. We advance that VD and ES approaches have fundamentally (metrically) different advantages and, hence, the comparative framework used and advocated here combines the accuracy afforded by ES with the precision provided by VD and permits the rapid identification of discrepancies with the potential to open new areas of discussion.
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Affiliation(s)
- Nicolás E Campione
- Palaeoscience Research Centre, University of New England, Armidale, New South Wales, 2351, Australia
| | - David C Evans
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks St, Toronto, Ontario, M5S 3B2, Canada.,Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario, M5S 2C6, Canada
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21
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Lovelace DM, Hartman SA, Mathewson PD, Linzmeier BJ, Porter WP. Modeling Dragons: Using linked mechanistic physiological and microclimate models to explore environmental, physiological, and morphological constraints on the early evolution of dinosaurs. PLoS One 2020; 15:e0223872. [PMID: 32469936 PMCID: PMC7259893 DOI: 10.1371/journal.pone.0223872] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 05/12/2020] [Indexed: 11/29/2022] Open
Abstract
We employed the widely-tested biophysiological modeling software, Niche Mapper™ to investigate the metabolic function of the Late Triassic dinosaurs Plateosaurus and Coelophysis during global greenhouse conditions. We tested a variety of assumptions about resting metabolic rate, each evaluated within six microclimate models that bound paleoenvironmental conditions at 12° N paleolatitude, as determined by sedimentological and isotopic proxies for climate within the Chinle Formation of the southwestern United States. Sensitivity testing of metabolic variables and simulated “metabolic chamber” analyses support elevated “ratite-like” metabolic rates and intermediate “monotreme-like” core temperature ranges in these species of early saurischian dinosaur. Our results suggest small theropods may have needed partial to full epidermal insulation in temperate environments, while fully grown prosauropods would have likely been heat stressed in open, hot environments and should have been restricted to cooler microclimates such as dense forests or higher latitudes and elevations. This is in agreement with the Late Triassic fossil record and may have contributed to the latitudinal gap in the Triassic prosauropod record.
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Affiliation(s)
- David M. Lovelace
- University of Wisconsin Geology Museum, Department of Geosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail: (DL); (WP)
| | - Scott A. Hartman
- Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Paul D. Mathewson
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Benjamin J. Linzmeier
- Department of Geoscience, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Warren P. Porter
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- * E-mail: (DL); (WP)
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Piechowski R, Tałanda M. The locomotor musculature and posture of the early dinosauriform Silesaurus opolensis provides a new look into the evolution of Dinosauromorpha. J Anat 2020; 236:1044-1100. [PMID: 32003023 DOI: 10.1111/joa.13155] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 11/27/2019] [Accepted: 12/29/2019] [Indexed: 11/30/2022] Open
Abstract
It is widely accepted that ornithodirans (bird lineage) and some pseudosuchians (crocodilian lineage) achieved fully erect limb posture in different ways. Ornithodirans have buttress-erected hindlimbs, while some advanced pseudosuchians have pillar-erected hindlimbs. Analysis of the musculoskeletal apparatus of the early dinosauriform Silesaurus opolensis challenges this view. This ornithodiran had pillar-erected hindlimbs like some pseudosuchians. This condition could be autapomorphic or represents a transitional state between adductor-controlled limb posture of early dinosauromorphs and the buttress-erected hindlimbs of dinosaurs. This sequence of changes is supported by Triassic tracks left by animals of the dinosaurian lineage. It was associated with the strong development of knee flexors and extensors. Furthermore, the forelimbs of Silesaurus were fully erect, analogously to those of early sauropods. Members of both lineages reduced the muscles related to the protraction, retraction and bending of the limb. They used forelimbs more as a body support and less for propulsion. A similar scapula and humerus construction can be found in the Lagerpetidae and Lewisuchus, suggesting that long, slender, fully erected forelimbs are primitive for all Dinosauromorpha, not just Silesauridae. Early dinosaurs redeveloped several muscle attachments on the forelimb, probably in relation to bipedality.
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Affiliation(s)
- Rafał Piechowski
- Institute of Paleobiology, Polish Academy of Sciences, Warsaw, Poland.,Department of Palaeobiology and Evolution, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
| | - Mateusz Tałanda
- Department of Palaeobiology and Evolution, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland
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Palma Liberona JA, Soto-Acuña S, Mendez MA, Vargas AO. Assesment and interpretation of negative forelimb allometry in the evolution of non-avian Theropoda. Front Zool 2019; 16:44. [PMID: 31827570 PMCID: PMC6889632 DOI: 10.1186/s12983-019-0342-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 10/29/2019] [Indexed: 12/28/2022] Open
Abstract
Background The origin of birds is marked by a significant decrease in body size along with an increase in relative forelimb size. However, before the evolution of flight, both traits may have already been related: It has been proposed that an evolutionary trend of negative forelimb allometry existed in non-avian Theropoda, such that larger species often have relatively shorter forelimbs. Nevertheless, several exceptions exist, calling for rigorous phylogenetic statistical testing. Results Here, we re-assessed allometric patterns in the evolution of non-avian theropods, for the first time taking into account the non-independence among related species due to shared evolutionary history.We confirmed a main evolutionary trend of negative forelimb allometry for non-avian Theropoda, but also found support that some specific subclades (Coelophysoidea, Ornithomimosauria, and Oviraptorosauria) exhibit allometric trends that are closer to isometry, losing the ancestral negative forelimb allometry present in Theropoda as a whole. Conclusions Explanations for negative forelimb allometry in the evolution of non-avian theropods have not been discussed, yet evolutionary allometric trends often reflect ontogenetic allometries, which suggests negative allometry of the forelimb in the ontogeny of most non-avian theropods. In modern birds, allometric growth of the limbs is related to locomotor and behavioral changes along ontogeny. After reviewing the evidence for such changes during the ontogeny of non-avian dinosaurs, we propose that proportionally longer arms of juveniles became adult traits in the small-sized and paedomorphic Aves.
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Affiliation(s)
- José A Palma Liberona
- 1Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile., Las Palmeras 3425, Santiago, Chile
| | - Sergio Soto-Acuña
- 1Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile., Las Palmeras 3425, Santiago, Chile
| | - Marco A Mendez
- 2Laboratorio de Genética y Evolución, Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile., Las Palmeras 3425, Santiago, Chile
| | - Alexander O Vargas
- 1Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile., Las Palmeras 3425, Santiago, Chile
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