1
|
Wang S, Ding N, Tan Q, Yang R, Zhang Q, Tan L. A new Urbacodon (Theropoda, Troodontidae) from the Upper Cretaceous Iren Dabasu Formation, China: Implications for troodontid phylogeny and tooth biology. Cladistics 2024. [PMID: 39016633 DOI: 10.1111/cla.12592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 05/11/2024] [Accepted: 05/16/2024] [Indexed: 07/18/2024] Open
Abstract
Tooth attachment and replacement play significant roles in the feeding ecology of polyphyodont vertebrates, yet these aspects have remained largely unexplored in non-avialan paravians including troodontids. Here, we describe a new troodontid species, Urbacodon norelli sp.n., recovered from the Upper Cretaceous Iren Dabasu Formation of Inner Mongolia, China, based on an incomplete right dentary and 12 associated replacement teeth. Urbacodon norelli is distinguished from all other known troodontids, including its relative U. itemirensis from Uzbekistan, by several features: the presence of paired dentary symphyseal foramina, the presence of a relatively steep anterior margin of the dentary, the absence of a dentary chin, the presence of a common groove hosting the anterior 12 dentary teeth, and the presence of relatively larger dentary teeth. Phylogenetic analysis places both species of Urbacodon as sister taxa to Zanabazar junior, confirming their status as later-diverging troodontids. Radiographs revealed an alternating tooth replacement pattern in U. norelli, with a maximum Zahnreihen-spacing estimated to be 3. During tooth replacement, the anteriorly inclined interdental septa, which wedge between anterior dentary teeth, underwent frequent remodelling as the developing tooth moved upwards, particularly anterolabially. This rapid turnover left insufficient time for an interdental plate to form, resulting in the absence of such structures in this specimen. The frequent remodelling of periodontal tissues accompanying tooth replacement is likely to account for the absence of interdental plates. The discovery of this new troodontid expands our understanding of paravian theropods from the Upper Cretaceous Iren Dabasu Formation and provides valuable insights into troodontid tooth biology.
Collapse
Affiliation(s)
- Shuo Wang
- Laboratory of Vertebrate Evolution, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Nuo Ding
- Laboratory of Vertebrate Evolution, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Qingwei Tan
- Long Hao Institute of Geology and Paleontology, Hohhot, Nei Mongol, 010010, China
| | - Rui Yang
- Laboratory of Vertebrate Evolution, School of Life Sciences, East China Normal University, Shanghai, 200241, China
| | - Qiyue Zhang
- State Key Laboratory of Cognitive Neuroscience and Learning & IDG/McGovern Institute for Brain Research, Beijing Normal University, Beijing, 100875, China
| | - Lin Tan
- Long Hao Institute of Geology and Paleontology, Hohhot, Nei Mongol, 010010, China
| |
Collapse
|
2
|
Pentland AH, Poropat SF, Duncan RJ, Kellner AWA, Bantim RAM, Bevitt JJ, Tait AM, Grice K. Haliskia peterseni, a new anhanguerian pterosaur from the late Early Cretaceous of Australia. Sci Rep 2024; 14:11789. [PMID: 38866826 PMCID: PMC11169243 DOI: 10.1038/s41598-024-60889-8] [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: 02/16/2024] [Accepted: 04/29/2024] [Indexed: 06/14/2024] Open
Abstract
Pterosaur remains have been reported from every continent; however, pterosaur skeletons remain rare. A new pterosaur is presented here, Haliskia peterseni gen. et sp. nov., constituting the most complete specimen from Australia from the upper Albian Toolebuc Formation of the Eromanga Basin (Queensland, Australia). A combination of features, including the presence of a premaxillary crest and curved teeth, and the morphology of the scapulocoracoid, support its referral to Anhangueria. Haliskia can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the 4th and 5th tooth pairs are smaller than the 3rd and 6th, and the 2nd and 5th alveoli are smaller than 3-4 and 6-8. Moreover, the hyoid is 70% the total length of the mandible. The phylogenetic analyses presented here place Haliskia within Anhangueria. In one analysis, Haliskia and Ferrodraco are resolved as sister taxa, with Tropeognathus mesembrinus sister to that clade. The other resolves Haliskia, Mythunga and Ferrodraco in a polytomy within Tropeognathinae. The new Australian pterosaur attests to the success of Anhangueria during the latest Early Cretaceous and suggests that the Australian forms were more taxonomically diverse and palaeobiogeographically complex than previously recognized.
Collapse
Affiliation(s)
- Adele H Pentland
- Western Australian Organic & Isotope Geochemistry Centre, School of Earth and Planetary Science, Curtin University, Bentley, Western Australia, 6102, Australia.
- Australian Age of Dinosaurs Museum of Natural History, The Jump-Up, Winton, Queensland, 4735, Australia.
| | - Stephen F Poropat
- Western Australian Organic & Isotope Geochemistry Centre, School of Earth and Planetary Science, Curtin University, Bentley, Western Australia, 6102, Australia
- Australian Age of Dinosaurs Museum of Natural History, The Jump-Up, Winton, Queensland, 4735, Australia
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, Victoria, 3800, Australia
| | - Ruairidh J Duncan
- School of Biological Sciences, Faculty of Science, Monash University, Clayton, Victoria, 3800, Australia
- Museums Victoria Research Institute, GPO Box 666, Melbourne, Victoria, 3001, Australia
| | - Alexander W A Kellner
- Laboratório de Sistemática e Tafonomia de Vertebrados Fósseis, Setor de Paleovertebrados, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renan A M Bantim
- Museu de Paleontologia Plácido Cidade Nuvens, Universidade Regional do Cariri, Santana do Cariri, Crato, Ceará, Brazil
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, 2234, Australia
| | - Alan M Tait
- Museums Victoria Research Institute, GPO Box 666, Melbourne, Victoria, 3001, Australia
| | - Kliti Grice
- Western Australian Organic & Isotope Geochemistry Centre, School of Earth and Planetary Science, Curtin University, Bentley, Western Australia, 6102, Australia
| |
Collapse
|
3
|
Hu J, Xu X, Li F, Han F. Tooth replacement in the early-diverging neornithischian Jeholosaurus shangyuanensis and implications for dental evolution and herbivorous adaptation in Ornithischia. BMC Ecol Evol 2024; 24:46. [PMID: 38627692 PMCID: PMC11020315 DOI: 10.1186/s12862-024-02233-2] [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: 01/22/2024] [Accepted: 03/28/2024] [Indexed: 04/19/2024] Open
Abstract
BACKGROUND Tooth replacement patterns of early-diverging ornithischians, which are important for understanding the evolution of the highly specialized dental systems in hadrosaurid and ceratopsid dinosaurs, are poorly known. The early-diverging neornithischian Jeholosaurus, a small, bipedal herbivorous dinosaur from the Early Cretaceous Jehol Biota, is an important taxon for understanding ornithischian dental evolution, but its dental morphology was only briefly described previously and its tooth replacement is poorly known. RESULTS CT scanning of six specimens representing different ontogenetic stages of Jeholosaurus reveals significant new information regarding the dental system of Jeholosaurus, including one or two replacement teeth in nearly all alveoli, relatively complete tooth resorption, and an increase in the numbers of alveoli and replacement teeth during ontogeny. Reconstructions of Zahnreihen indicate that the replacement pattern of the maxillary dentition is similar to that of the dentary dentition but with a cyclical difference. The maxillary tooth replacement rate in Jeholosaurus is probably 46 days, which is faster than that of most other early-diverging ornithischians. During the ontogeny of Jeholosaurus, the premaxillary tooth replacement rate slows from 25 days to 33 days with similar daily dentine formation. CONCLUSIONS The tooth replacement rate exhibits a decreasing trend with ontogeny, as in Alligator. In a phylogenetic context, fast tooth replacement and multi-generation replacement teeth have evolved at least twice independently in Ornithopoda, and our analyses suggest that the early-diverging members of the major ornithischian clades exhibit different tooth replacement patterns as an adaption to herbivory.
Collapse
Affiliation(s)
- Jinfeng Hu
- School of Earth Sciences, China University of Geosciences, 388 Lumo Road, 430074, Wuhan, Hubei Province, China
| | - Xing Xu
- Center for Vertebrate Evolutionary Biology, Yunnan University, Kunming, China
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | - Fuqiang Li
- Yifu Museum of China University of Geosciences, Wuhan, Hubei, China
| | - Fenglu Han
- School of Earth Sciences, China University of Geosciences, 388 Lumo Road, 430074, Wuhan, Hubei Province, China.
| |
Collapse
|
4
|
Cerda IA, Codorniú L. Palaeohistology reveals an unusual periodontium and tooth implantation in a filter-feeding pterodactyloid pterosaur, Pterodaustro guinazui, from the Lower Cretaceous of Argentina. J Anat 2023; 243:579-589. [PMID: 37059589 PMCID: PMC10485577 DOI: 10.1111/joa.13878] [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: 02/23/2023] [Revised: 03/30/2023] [Accepted: 03/31/2023] [Indexed: 04/16/2023] Open
Abstract
Pterosaurs are an extinct group of Mesozoic flying reptiles, which exhibited high diversity with regard to their dentition. Although morphological features of pterosaur dentition have been described in detail in several contributions, the histology of tooth and tooth attachment tissues (i.e. periodontium) has been scarcely analysed to date for this clade. Here we describe and interpret the microstructure of the tooth and periodontium attachment tissues of Pterodaustro guinazui, a filter-feeding pterodactyloid pterosaur from the Lower Cretaceous of Argentina. The histological analysis of the lower jaw and its filamentous teeth verifies that the geometry of the implantation corresponds to an aulacodont condition (i.e. teeth are set in a groove with no interdental separation). This pattern departs from that recorded in other archosaurs, being possibly also present in other, non-closely related, pterosaurs. Regarding tooth attachment, in contrast to other pterosaurs, there is no direct evidence for gomphosis in Pterodaustro (i.e. the absence of cementum, mineralized periodontal ligamentum and alveolar bone). Nevertheless, the current evidence for ankylosis is still not conclusive. Contrary to that reported for other archosaurs, replacement teeth are absent in Pterodaustro, which is interpreted as evidence for monophyodonty or diphyodonty in this taxon. Most of the microstructural features are possibly related to the complex filter-feeding apparatus of Pterodaustro and does not appear to represent the general pattern of pterosaurs.
Collapse
Affiliation(s)
- Ignacio A Cerda
- Consejo Nacional de Investigación Ciencia y Técnica (CONICET), Buenos Aires, Argentina
- Instituto de Investigación en Paleobiología y Geología (IIPG), Universidad Nacional de Río Negro (UNRN), Museo Carlos Ameghino, Cipolletti, Río Negro, Argentina
| | - Laura Codorniú
- Consejo Nacional de Investigación Ciencia y Técnica (CONICET), Buenos Aires, Argentina
- Departamento de Geología, Universidad Nacional de San Luis, San Luis, Argentina
| |
Collapse
|
5
|
Hu J, Forster CA, Xu X, Zhao Q, He Y, Han F. Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians. eLife 2022; 11:76676. [PMID: 35441592 PMCID: PMC9068210 DOI: 10.7554/elife.76676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 04/19/2022] [Indexed: 11/30/2022] Open
Abstract
The dental system of ceratopsids is among the most specialized structure in Dinosauria by the presence of tooth batteries and high-angled wear surfaces. However, the origin of this unique dental system is poorly understood due to a lack of relevant knowledge in early-diverging ceratopsians. Here, we study the dental system of three earliest-diverging Chinese ceratopsians: Yinlong and Hualianceratops from the early Late Jurassic of Xinjiang and Chaoyangsaurus from the Late Jurassic of Liaoning Province. By micro-computed tomographic analyses, our study has revealed significant new information regarding the dental system, including no more than five replacement teeth in each jaw quadrant; at most one replacement tooth in each alveolus; nearly full resorption of the functional tooth root; and occlusion with low-angled, concave wear facets. Yinlong displays an increase in the number of maxillary alveoli and a decrease in the number of replacement teeth during ontogeny as well as the retention of functional tooth remnants in the largest individual. Chaoyangsaurus and Hualianceratops have slightly more replacement teeth than Yinlong. In general, early-diverging ceratopsians display a relatively slow tooth replacement rate and likely use gastroliths to triturate foodstuffs. The difference in dietary strategy might have influenced the tooth replacement pattern in later-diverging ceratopsians.
Collapse
Affiliation(s)
- Jinfeng Hu
- School of Earth Sciences, China University of Geosciences, Wuhan, China
| | - Catherine A Forster
- Department of Biological Sciences, The George Washington University, Washington, United States
| | - Xing Xu
- Chinese Academy of Sciences, Beijing, China
| | - Qi Zhao
- Chinese Academy of Sciences, Beijing, China
| | - Yiming He
- Nanjiang Museum of Paleontology, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China
| | - Fenglu Han
- School of Earth Sciences, China University of Geosciences, Wuhan, China
| |
Collapse
|
6
|
Liao JL, Lan T, Xu GH, Li J, Qin YJ, Zhao MS, Li YL, Wang Y. Tooth Structure and Replacement of the Triassic Keichousaurus (Sauropterygia, Reptilia) From South China. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.741851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The small-sized sauropterygian Keichousaurus hui was one of the most abundant marine reptiles from the Triassic Yangtze Sea in South China. Although Keichousaurus has been studied in many aspects, including the osteology, ontogeny, sexual dimorphism, and reproduction, the dentition of this marine reptile was only briefly described in external morphology. In this study, we provide new information on Keichousaurus tooth implantation, histology, and replacement based on a detailed examination of well-preserved specimens collected in the past decades. The tooth histology has been investigated for the first time by analyzing cross-sections of premaxillary teeth and the tooth attachment and implantation have been further revealed by X-ray computed microtomography. We refer the tooth replacement of Keichousaurus to the iguanid replacement type on the basis of the observed invasion of small replacement tooth into the pulp cavity of the functional tooth. Given the resemblance to other extinct and modern piscivorous predators in the morphology and structure of teeth, Keichousaurus might mainly feed on small or juvenile fishes and some relatively soft-bodied invertebrates (e.g., mysidacean shrimps) from the same ecosystem.
Collapse
|
7
|
Wu YH, Chiappe LM, Bottjer DJ, Nava W, Martinelli AG. Dental replacement in Mesozoic birds: evidence from newly discovered Brazilian enantiornithines. Sci Rep 2021; 11:19349. [PMID: 34593843 PMCID: PMC8484441 DOI: 10.1038/s41598-021-98335-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 08/24/2021] [Indexed: 02/08/2023] Open
Abstract
Polyphyodonty-multiple tooth generations-in Mesozoic birds has been confirmed since the nineteenth century. Their dental cycle had been assessed through sparse data from tooth roots revealed through broken jawbones and disattached teeth. However, detailed descriptions of their tooth cycling are lacking, and the specifics of their replacement patterns remain largely unknown. Here we present unprecedented µCT data from three enantiornithine specimens from the Upper Cretaceous of southeastern Brazil. The high resolution µCT data show an alternating dental replacement pattern in the premaxillae, consistent with the widespread pattern amongst extinct and extant reptiles. The dentary also reveals dental replacement at different stages. These results strongly suggest that an alternating pattern was typical of enantiornithine birds. µCT data show that new teeth start lingually within the alveoli, resorb roots of functional teeth and migrate labially into their pulp cavities at an early stage, similar to modern crocodilians. Our results imply that the control mechanism for tooth cycling is conserved during the transition between non-avian reptiles and birds. These first 3D reconstructions of enantiornithine dental replacement demonstrate that 3D data are essential to understand the evolution and deep homology of archosaurian tooth cycling.
Collapse
Affiliation(s)
- Yun-Hsin Wu
- grid.243983.70000 0001 2302 4724Natural History Museum of Los Angeles County, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853University of Southern California, Los Angeles, CA USA
| | - Luis M. Chiappe
- grid.243983.70000 0001 2302 4724Natural History Museum of Los Angeles County, Los Angeles, CA USA
| | - David J. Bottjer
- grid.42505.360000 0001 2156 6853University of Southern California, Los Angeles, CA USA
| | - William Nava
- Museu de Paleontologia de Marília, Marília, São Paulo, Brazil
| | - Agustín G. Martinelli
- grid.459814.50000 0000 9653 9457Museo Argentino Ciencias Naturales “Bernardino Rivadavia”, Buenos Aires, Argentina
| |
Collapse
|
8
|
Brink KS, Henríquez JI, Grieco TM, Martin del Campo JR, Fu K, Richman JM. Tooth Removal in the Leopard Gecko and the de novo Formation of Replacement Teeth. Front Physiol 2021; 12:576816. [PMID: 34012403 PMCID: PMC8126719 DOI: 10.3389/fphys.2021.576816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 03/25/2021] [Indexed: 11/13/2022] Open
Abstract
Many reptiles are able to continuously replace their teeth through life, an ability attributed to the existence of epithelial stem cells. Tooth replacement occurs in a spatially and temporally regulated manner, suggesting the involvement of diffusible factors, potentially over long distances. Here, we locally disrupted tooth replacement in the leopard gecko (Eublepharis macularius) and followed the recovery of the dentition. We looked at the effects on local patterning and functionally tested whether putative epithelial stem cells can give rise to multiple cell types in the enamel organs of new teeth. Second generation teeth with enamel and dentine were removed from adult geckos. The dental lamina was either left intact or disrupted in order to interfere with local patterning cues. The dentition began to reform by 1 month and was nearly recovered by 2-3 months as shown in μCT scans and eruption of teeth labeled with fluorescent markers. Microscopic analysis showed that the dental lamina was fully healed by 1 month. The deepest parts of the dental lamina retained odontogenic identity as shown by PITX2 staining. A pulse-chase was carried out to label cells that were stimulated to enter the cell cycle and then would carry BrdU forward into subsequent tooth generations. Initially we labeled 70-78% of PCNA cells with BrdU. After a 1-month chase, the percentage of BrdU + PCNA labeled cells in the dental lamina had dropped to 10%, consistent with the dilution of the label. There was also a population of single, BrdU-labeled cells present up to 2 months post surgery. These BrdU-labeled cells were almost entirely located in the dental lamina and were the likely progenitor/stem cells because they had not entered the cell cycle. In contrast fragmented BrdU was seen in the PCNA-positive, proliferating enamel organs. Homeostasis and recovery of the gecko dentition was therefore mediated by a stable population of epithelial stem cells in the dental lamina.
Collapse
Affiliation(s)
| | | | | | | | | | - Joy M. Richman
- Department of Oral Health Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
9
|
Brink KS, Wu P, Chuong CM, Richman JM. The Effects of Premature Tooth Extraction and Damage on Replacement Timing in the Green Iguana. Integr Comp Biol 2020; 60:581-593. [PMID: 32974642 PMCID: PMC7546963 DOI: 10.1093/icb/icaa099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Reptiles with continuous tooth replacement, or polyphyodonty, replace their teeth in predictable, well-timed waves in alternating tooth positions around the mouth. This process is thought to occur irrespective of tooth wear or breakage. In this study, we aimed to determine if damage to teeth and premature tooth extraction affects tooth replacement timing long-term in juvenile green iguanas (Iguana iguana). First, we examined normal tooth development histologically using a BrdU pulse-chase analysis to detect label-retaining cells in replacement teeth and dental tissues. Next, we performed tooth extraction experiments for characterization of dental tissues after functional tooth (FT) extraction, including proliferation and β-Catenin expression, for up to 12 weeks. We then compared these results to a newly analyzed historical dataset of X-rays collected up to 7 months after FT damage and extraction in the green iguana. Results show that proliferation in the dental and successional lamina (SL) does not change after extraction of the FT, and proliferation occurs in the SL only when a tooth differentiates. Damage to an FT crown does not affect the timing of the tooth replacement cycle, however, complete extraction shifts the replacement cycle ahead by 4 weeks by removing the need for resorption of the FT. These results suggest that traumatic FT loss affects the timing of the replacement cycle at that one position, which may have implications for tooth replacement patterning around the entire mouth.
Collapse
Affiliation(s)
- Kirstin S Brink
- Department of Oral Health Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Department of Geological Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, MB R3T 2N2, Canada
| | - Ping Wu
- Keck School of Medicine, University of Southern California, 2011 Zonal Ave, Los Angeles, CA HMR313, USA
| | - Cheng-Ming Chuong
- Keck School of Medicine, University of Southern California, 2011 Zonal Ave, Los Angeles, CA HMR313, USA
| | - Joy M Richman
- Department of Oral Health Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| |
Collapse
|
10
|
Ferrodraco lentoni gen. et sp. nov., a new ornithocheirid pterosaur from the Winton Formation (Cenomanian-lower Turonian) of Queensland, Australia. Sci Rep 2019; 9:13454. [PMID: 31582757 PMCID: PMC6776501 DOI: 10.1038/s41598-019-49789-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 08/30/2019] [Indexed: 11/08/2022] Open
Abstract
The Australian pterosaur record is poor by world standards, comprising fewer than 20 fragmentary specimens. Herein, we describe the new genus and species Ferrodraco lentoni gen. et sp. nov., based on the most complete pterosaur specimen ever found in Australia, and the first reported from the Winton Formation (Cenomanian–lower Turonian). The presence of premaxillary and mandibular crests, and spike-shaped teeth with subcircular bases, enable Ferrodraco to be referred to Anhangueria. Ferrodraco can be distinguished from all other anhanguerian pterosaurs based on two dental characters: the first premaxillary and mandibular tooth pairs are small; and the fourth–seventh tooth pairs are smaller than the third and eighth ones. Ferrodraco was included in a phylogenetic analysis of Pterosauria and resolved as the sister taxon to Mythunga camara (upper Albian Toolebuc Formation, Australia), with that clade occupying the most derived position within Ornithocheiridae. Ornithocheirus simus (Albian Cambridge Greensand, England), Coloborhynchus clavirostris (Valanginian Hastings Sands, England), and Tropeognathus mesembrinus (upper Aptian–lower Albian Romualdo Formation, Brazil) were resolved as successive sister taxa, which suggests that ornithocheirids were cosmopolitan during the Albian–Cenomanian. Furthermore, the stratigraphic age of Ferrodraco lentoni (Cenomanian–lower Turonian) implies that anhanguerians might have survived later in Australia than elsewhere.
Collapse
|
11
|
Hanai T, Tsuihiji T. Description of Tooth Ontogeny and Replacement Patterns in a Juvenile Tarbosaurus bataar (Dinosauria: Theropoda) Using CT-Scan Data. Anat Rec (Hoboken) 2018; 302:1210-1225. [PMID: 30378771 DOI: 10.1002/ar.24014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 07/16/2018] [Accepted: 08/01/2018] [Indexed: 11/08/2022]
Abstract
Teeth are continually replaced in most of non-mammalian gnathostomes to maintain their functional dentitions. To clarify the tooth replacement patterns in tyrannosaurid theropod dinosaurs, we examined well-preserved dentitions (both premaxillae, left maxilla, partial right maxilla, and both dentaries) of a juvenile Tarbosaurus bataar (MPC-D 107/7) using X-ray computed tomographic (CT) imaging. Three-dimensional (3D) rendering of the dentitions and staging of replacement teeth allowed quantitative analyses of the tooth ontogeny and replacement patterns in this specimen. These strategies were validated by comparing the results between MPC-D 107/7 and extant crocodilians, which are taxa that have previously been studied using non-CT methods. 3D-rendered dentitions of MPC-D 107/7 showed alternate replacement patterns between odd- and even-numbered alveoli. Such patterns were discontinuous at the premaxilla-maxilla junctions, suggesting the division of replacement patterns between the two dentitions possessing morpho-functionally different features. The replacement process in the odd-numbered alveoli of the left maxilla sequentially proceeded from distal alveoli. Meanwhile, in the both dentaries, there were simple alternate patterns in which functional teeth would be simultaneously shed out in every second alveoli. Such a simple alternation had never been reported in the adult tyrannosaurid dentaries. Under this pattern, the half of functional teeth in a single dentition would be shed at the same time, which may hamper foraging functions. We conclude that the simple alternate patterns found in the dentary dentitions of MPC-D 107/7 represent transient condition in juvenile tyrannosaurids, suggesting ontogenetic changes in tooth replacement patterns in the tyrannosaurid dentary. Anat Rec, 302:1210-1225, 2019. © 2018 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Tomoya Hanai
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| | - Takanobu Tsuihiji
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
12
|
He Y, Makovicky PJ, Xu X, You H. High-resolution computed tomographic analysis of tooth replacement pattern of the basal neoceratopsian Liaoceratops yanzigouensis informs ceratopsian dental evolution. Sci Rep 2018; 8:5870. [PMID: 29651146 PMCID: PMC5897341 DOI: 10.1038/s41598-018-24283-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
The dental morphology and tooth replacement pattern of Liaoceratops yanzigouensis, the earliest known neoceratopsian, are important for our understanding of the evolution of the ceratopsian dental system. Here we describe the dental morphology and tooth replacement of Liaoceratops yanzigouensis based on high-resolution computed tomographic (CT) scan data of three specimens including the holotype, the first study for basal ceratopsian. The three-dimensional reconstructions reveal some important new information, including: three teeth in the premaxilla in one side, two more teeth in the dentary than in the maxilla, incipiently developed mesial grooves on some crowns, two generations of replacement teeth within some tooth families; and most functional teeth were under heavy resorption by the replacement process, but still remained functional. Comparisons of tooth pair positions from opposite sides in the four jaw quadrants of three specimens revealed a degree of bilateral symmetry in replacement pattern. Reconstruction of Zahnreihen yields an avergae z-spacing of 2.58 with simultaneous front-to-back tooth replacement. Our study presents the earliest evidence of derived neoceratopsian traits of the complex dental batteries in ceratopsids. Most significantly, our models reveal the tracts of partially resorbed functional teeth which appears to track the growth of the jaws, traits previously undocumented in Ceratopsia.
Collapse
Affiliation(s)
- Yiming He
- School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu, 210046, China.
| | - Peter J Makovicky
- Department of Geology, The Field Museum, Chicago, llinois, 60640, United States of America
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Palaeontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100046, China
| | - Hailu You
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Palaeontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100046, China
| |
Collapse
|
13
|
NORMAN DAVIDB, CROMPTON ALFREDW, BUTLER RICHARDJ, PORRO LAURAB, CHARIG ALANJ. The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial anatomy, functional morphology, taxonomy, and relationships. Zool J Linn Soc 2011. [DOI: 10.1111/j.1096-3642.2011.00697.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|