1
|
Urban CA, Legendre LJ, Clarke JA. Description of natal down of the ostrich (Struthio camelus) and comparison with common quail (Coturnix coturnix): Developmental and evolutionary implications. J Anat 2023; 243:1007-1023. [PMID: 37515428 PMCID: PMC10641043 DOI: 10.1111/joa.13936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/18/2023] [Accepted: 07/13/2023] [Indexed: 07/30/2023] Open
Abstract
Natal down is a feather stage that differs in both form and function from the definitive feathers of adult birds. It has a simpler structure that has been speculated to be similar to the body coverings of non-avian dinosaurs. However, inference of the evolution of natal down has been limited by our understanding of its structural variation in extant birds. Most descriptive work has focused on neognathous birds, limiting our knowledge of the full diversity of feathers in extant taxa. Here, we describe the natal down of a post-hatch ostrich (Struthio camelus) and compare it to that of a post-hatch quail (Coturnix coturnix). We confirm the presence of featherless spaces (apteria) in S. camelus and the lack of barbules on the tips of natal down in both species. We also find differences between dorsal and ventral natal down structures, such as barbule density in S. camelus and the extent of the bare portion of the barb in both species. Surprisingly, we do not find that the neoptiles of either species follow the ideal morphologies for increasing insulation. Finally, we hypothesize that the different barb types present in S. camelus natal down result from a large addition of new barb ridges during development, which is not known except in feathers with a rachis. These results have implications for our understanding of how structure informs function and development in understudied feather types, such as those shared by non-avian dinosaurs.
Collapse
Affiliation(s)
- Carmen A Urban
- Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Lucas J Legendre
- Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| | - Julia A Clarke
- Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA
| |
Collapse
|
2
|
Widrig KE, Bhullar BS, Field DJ. 3D atlas of tinamou (Neornithes: Tinamidae) pectoral morphology: Implications for reconstructing the ancestral neornithine flight apparatus. J Anat 2023; 243:729-757. [PMID: 37358291 PMCID: PMC10557402 DOI: 10.1111/joa.13919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 06/06/2023] [Accepted: 06/12/2023] [Indexed: 06/27/2023] Open
Abstract
Palaeognathae, the extant avian clade comprising the flightless ratites and flight-capable tinamous (Tinamidae), is the sister group to all other living birds, and recent phylogenetic studies illustrate that tinamous are phylogenetically nested within a paraphyletic assemblage of ratites. As the only extant palaeognaths that have retained the ability to fly, tinamous may provide key information on the nature of the flight apparatus of ancestral crown palaeognaths-and, in turn, crown birds-as well as insight into convergent modifications to the wing apparatus among extant ratite lineages. To reveal new information about the musculoskeletal anatomy of tinamous and facilitate development of computational biomechanical models of tinamou wing function, we generated a three-dimensional musculoskeletal model of the flight apparatus of the extant Andean tinamou (Nothoprocta pentlandii) using diffusible iodine-based contrast-enhanced computed tomography (diceCT). Origins and insertions of the pectoral flight musculature of N. pentlandii are generally consistent with those of other extant volant birds specialized for burst flight, and the entire suite of presumed ancestral neornithine flight muscles are present in N. pentlandii with the exception of the biceps slip. The pectoralis and supracoracoideus muscles are robust, similar to the condition in other extant burst-flying birds such as many extant Galliformes. Contrary to the condition in most extant Neognathae (the sister clade to Palaeognathae), the insertion of the pronator superficialis has a greater distal extent than the pronator profundus, although most other anatomical observations are broadly consistent with the conditions observed in extant neognaths. This work will help form a basis for future comparative studies of the avian musculoskeletal system, with implications for reconstructing the flight apparatus of ancestral crown birds and clarifying musculoskeletal modifications underlying the convergent origins of ratite flightlessness.
Collapse
Affiliation(s)
- Klara E. Widrig
- Department of Earth SciencesUniversity of CambridgeCambridgeUK
| | - Bhart‐Anjan S. Bhullar
- Department of Earth and Planetary SciencesYale UniversityNew HavenConnecticutUSA
- Peabody Museum of Natural HistoryYale UniversityNew HavenConnecticutUSA
| | - Daniel J. Field
- Department of Earth SciencesUniversity of CambridgeCambridgeUK
- Museum of ZoologyUniversity of CambridgeCambridgeUK
| |
Collapse
|
3
|
Jensen TR, Zeiträg C, Osvath M. The selfish preen: absence of allopreening in Palaeognathae and its socio-cognitive implications. Anim Cogn 2023; 26:1467-1476. [PMID: 37256500 PMCID: PMC10442270 DOI: 10.1007/s10071-023-01794-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 06/01/2023]
Abstract
Preening behaviours are widespread in extant birds. While most birds appear to autopreen (self-directed preening), allopreening (preening directed at conspecifics) seems to have emerged only in certain species, but across many families. Allopreening has been hypothesised to reinforce mutual relationships and cooperation between individuals, and to underpin various socio-cognitive abilities. Palaeognathae is a bird group exhibiting neurocognitively plesiomorphic traits compared to other birds. They share many features with non-avian paravian dinosaurs and are thus important for the study of cognitive evolution in birds. Despite this, and the important correlation of allopreening with many complicated social behaviours, allopreening has not been systematically studied in Palaeognathae. Therefore, we examined the preening behaviours in four species of palaeognaths: common ostriches (Struthio camelus), greater rheas (Rhea americana), emus (Dromaius novaehollandiae), and elegant crested tinamous (Eudromia elegans). We compared findings with common ravens (Corvus corax), a neognath species known for its allopreening and complex social cognition. We found autopreening, but no allopreening, in the palaeognath species, while both autopreening and allopreening was found in common ravens. The absence of allopreening in Palaeognathae suggests an emergence of this behaviour within Neognathae. We contextualise our results in relation to the socio-cognitive underpinnings of allopreening and its implications for the understanding of the evolution of socio-cognitive abilities in non-avian paravian dinosaurs and early birds.
Collapse
Affiliation(s)
- Thomas Rejsenhus Jensen
- Department of Philosophy, Cognitive Science, Cognitive Zoology Group, Lund University, Lund, Sweden.
| | - Claudia Zeiträg
- Department of Philosophy, Cognitive Science, Cognitive Zoology Group, Lund University, Lund, Sweden
| | - Mathias Osvath
- Department of Philosophy, Cognitive Science, Cognitive Zoology Group, Lund University, Lund, Sweden
| |
Collapse
|
4
|
Lo Coco GE, Motta MJ, Agnolín FL, Novas FE. Wing osteology, myology, and function of Rhea americana (Aves, Rheidae). J Morphol 2022; 283:1015-1047. [PMID: 35673834 DOI: 10.1002/jmor.21486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 04/29/2022] [Accepted: 05/20/2022] [Indexed: 11/11/2022]
Abstract
The Greater Rhea (Rhea americana, Rheidae) is a flightless paleognath with a wide geographical distribution in South America. The morphology of its shoulder girdle and wings are different from those of flying birds and some characteristics are similar to basal birds and paravian theropods. We present a detailed osteological, myological, and functional study of the shoulder and the wing of the Greater Rhea. Particular features of the anatomy of the pectoral girdle and wing of Rhea include the lack of triosseal canal, reduced origin area of the mm. pectoralis p. thoracica and supracoracoideus and the lack of a propatagium. The wing muscle mass is markedly reduced, reaching only 0.89% of total body mass (BM). Forelimb muscles mass values are low compared to those of flying birds and are congruent with the non-use of wings for active locomotion movements. R. americana does not flap the wings dorso-ventral as typical for flying birds, but predominantly in cranio-caudal direction, following a craniolateral to caudomedial abduction-adduction arc. When the wings are fully abducted, they are inverted L-shaped, with the inner surface caudally faced, and when the wings are folded against the body, they do not perform the complete automatic wing folding nor the circumduction of the manus, a movement performed by extant volant birds. This study complements our knowledge of the axial musculature of the flightless paleognaths and highlights the use of the Greater Rhea as a model, which may help understand the evolution of Palaeognathae, as well as the origin of flapping flight among paravian theropods.
Collapse
Affiliation(s)
- Gastón E Lo Coco
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Buenos Aires, Argentina
| | - Matías J Motta
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Buenos Aires, Argentina
| | - Federico L Agnolín
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Buenos Aires, Argentina.,Departamento de Ciencias Naturales y Antropología, Fundación de Historia Natural "Félix de Azara", Universidad Maimónides, Buenos Aires, Argentina
| | - Fernando E Novas
- Laboratorio de Anatomía Comparada y Evolución de los Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Consejo Nacional de Investigaciones Científicas y Técnicas - CONICET, Buenos Aires, Argentina
| |
Collapse
|
5
|
Molloy EK, Gatesy J, Springer MS. Theoretical and practical considerations when using retroelement insertions to estimate species trees in the anomaly zone. Syst Biol 2021; 71:721-740. [PMID: 34677617 DOI: 10.1093/sysbio/syab086] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Accepted: 10/11/2021] [Indexed: 11/13/2022] Open
Abstract
A potential shortcoming of concatenation methods for species tree estimation is their failure to account for incomplete lineage sorting. Coalescent methods address this problem but make various assumptions that, if violated, can result in worse performance than concatenation. Given the challenges of analyzing DNA sequences with both concatenation and coalescent methods, retroelement insertions (RIs) have emerged as powerful phylogenomic markers for species tree estimation. Here, we show that two recently proposed quartet-based methods, SDPquartets and ASTRAL_BP, are statistically consistent estimators of the unrooted species tree topology under the coalescent when RIs follow a neutral infinite-sites model of mutation and the expected number of new RIs per generation is constant across the species tree. The accuracy of these (and other) methods for inferring species trees from RIs has yet to be assessed on simulated data sets, where the true species tree topology is known. Therefore, we evaluated eight methods given RIs simulated from four model species trees, all of which have short branches and at least three of which are in the anomaly zone. In our simulation study, ASTRAL_BP and SDPquartets always recovered the correct species tree topology when given a sufficiently large number of RIs, as predicted. A distance-based method (ASTRID_BP) and Dollo parsimony also performed well in recovering the species tree topology. In contrast, unordered, polymorphism, and Camin-Sokal parsimony typically fail to recover the correct species tree topology in anomaly zone situations with more than four ingroup taxa. Of the methods studied, only ASTRAL_BP automatically estimates internal branch lengths (in coalescent units) and support values (i.e. local posterior probabilities). We examined the accuracy of branch length estimation, finding that estimated lengths were accurate for short branches but upwardly biased otherwise. This led us to derive the maximum likelihood (branch length) estimate for when RIs are given as input instead of binary gene trees; this corrected formula produced accurate estimates of branch lengths in our simulation study, provided that a sufficiently large number of RIs were given as input. Lastly, we evaluated the impact of data quantity on species tree estimation by repeating the above experiments with input sizes varying from 100 to 100 000 parsimony-informative RIs. We found that, when given just 1 000 parsimony-informative RIs as input, ASTRAL_BP successfully reconstructed major clades (i.e clades separated by branches > 0.3 CUs) with high support and identified rapid radiations (i.e. shorter connected branches), although not their precise branching order. The local posterior probability was effective for controlling false positive branches in these scenarios.
Collapse
Affiliation(s)
- Erin K Molloy
- Department of Computer Science, University of Maryland, College Park, College Park, 20742, USA
| | - John Gatesy
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, 10024, USA
| | - Mark S Springer
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, Riverside, 92521, USA
| |
Collapse
|
6
|
Abstract
It has been reported that adult ostriches displayed the longest episodes of rapid eye movement (REM) sleep (up to 5 min) and more REM sleep (24% of the nighttime) than any other bird species. If the mammalian ontogenetic trend exists in the ostrich, then the amounts of REM and the duration of sleep episodes in young ostriches may be greater than those reported in adults. We investigated sleep in 1.5-3.5 month old ostrich chicks. Recordings were conducted during nighttime (20:00-08:00), the main sleep period in ostriches, which are diurnal. The polygrams were scored in 4-s epochs for waking, non-rapid eye movement (NREM) sleep and REM sleep, as in other bird studies. REM sleep in ostrich chicks occurred during both cortical EEG activation and during slow waves, as was described in adult ostriches. The chicks spent 69.3% ± 1.5% of the night in NREM sleep. REM sleep occupied 14.1% ± 1.8% of the night or 16.8% ± 2.0% of nighttime sleep. Episodes of REM sleep lasted on average 10 ± 1 s and ranged between 4 and 40 s. Therefore, the total amount and duration of REM sleep episodes in ostrich chicks were substantially smaller than reported in adult ostriches while the amounts of NREM sleep did not greatly differ. The developmental profile of REM sleep ontogenesis in the ostrich may be remarkably different from what has been reported in all studied mammals and birds.
Collapse
Affiliation(s)
- Oleg I Lyamin
- Department of Psychiatry, University of California Los Angeles, Los Angeles, CA.,Greater Los Angeles Healthcare System, North Hills, CA.,A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia
| | | | - Jerome M Siegel
- Department of Psychiatry, University of California Los Angeles, Los Angeles, CA.,Greater Los Angeles Healthcare System, North Hills, CA
| |
Collapse
|
7
|
Urantówka AD, Kroczak A, Mackiewicz P. New view on the organization and evolution of Palaeognathae mitogenomes poses the question on the ancestral gene rearrangement in Aves. BMC Genomics 2020; 21:874. [PMID: 33287726 PMCID: PMC7720580 DOI: 10.1186/s12864-020-07284-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/26/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bird mitogenomes differ from other vertebrates in gene rearrangement. The most common avian gene order, identified first in Gallus gallus, is considered ancestral for all Aves. However, other rearrangements including a duplicated control region and neighboring genes have been reported in many representatives of avian orders. The repeated regions can be easily overlooked due to inappropriate DNA amplification or genome sequencing. This raises a question about the actual prevalence of mitogenomic duplications and the validity of the current view on the avian mitogenome evolution. In this context, Palaeognathae is especially interesting because is sister to all other living birds, i.e. Neognathae. So far, a unique duplicated region has been found in one palaeognath mitogenome, that of Eudromia elegans. RESULTS Therefore, we applied an appropriate PCR strategy to look for omitted duplications in other palaeognaths. The analyses revealed the duplicated control regions with adjacent genes in Crypturellus, Rhea and Struthio as well as ND6 pseudogene in three moas. The copies are very similar and were subjected to concerted evolution. Mapping the presence and absence of duplication onto the Palaeognathae phylogeny indicates that the duplication was an ancestral state for this avian group. This feature was inherited by early diverged lineages and lost two times in others. Comparison of incongruent phylogenetic trees based on mitochondrial and nuclear sequences showed that two variants of mitogenomes could exist in the evolution of palaeognaths. Data collected for other avian mitogenomes revealed that the last common ancestor of all birds and early diverging lineages of Neoaves could also possess the mitogenomic duplication. CONCLUSIONS The duplicated control regions with adjacent genes are more common in avian mitochondrial genomes than it was previously thought. These two regions could increase effectiveness of replication and transcription as well as the number of replicating mitogenomes per organelle. In consequence, energy production by mitochondria may be also more efficient. However, further physiological and molecular analyses are necessary to assess the potential selective advantages of the mitogenome duplications.
Collapse
Affiliation(s)
- Adam Dawid Urantówka
- Department of Genetics, Wroclaw University of Environmental and Life Sciences, 7 Kozuchowska Street, 51-631 Wroclaw, Poland
| | - Aleksandra Kroczak
- Department of Genetics, Wroclaw University of Environmental and Life Sciences, 7 Kozuchowska Street, 51-631 Wroclaw, Poland
- Department of Bioinformatics and Genomics, Faculty of Biotechnology, University of Wrocław, 14a Fryderyka Joliot-Curie Street, 50-383 Wrocław, Poland
| | - Paweł Mackiewicz
- Department of Bioinformatics and Genomics, Faculty of Biotechnology, University of Wrocław, 14a Fryderyka Joliot-Curie Street, 50-383 Wrocław, Poland
| |
Collapse
|
8
|
McInerney PL, Lee MSY, Clement AM, Worthy TH. The phylogenetic significance of the morphology of the syrinx, hyoid and larynx, of the southern cassowary, Casuarius casuarius (Aves, Palaeognathae). BMC Evol Biol 2019; 19:233. [PMID: 31881941 DOI: 10.1186/s12862-019-1544-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 11/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Palaeognathae is a basal clade within Aves and include the large and flightless ratites and the smaller, volant tinamous. Although much research has been conducted on various aspects of palaeognath morphology, ecology, and evolutionary history, there are still areas which require investigation. This study aimed to fill gaps in our knowledge of the Southern Cassowary, Casuarius casuarius, for which information on the skeletal systems of the syrinx, hyoid and larynx is lacking - despite these structures having been recognised as performing key functional roles associated with vocalisation, respiration and feeding. Previous research into the syrinx and hyoid have also indicated these structures to be valuable for determining evolutionary relationships among neognath taxa, and thus suggest they would also be informative for palaeognath phylogenetic analyses, which still exhibits strong conflict between morphological and molecular trees. RESULTS The morphology of the syrinx, hyoid and larynx of C. casuarius is described from CT scans. The syrinx is of the simple tracheo-bronchial syrinx type, lacking specialised elements such as the pessulus; the hyoid is relatively short with longer ceratobranchials compared to epibranchials; and the larynx is comprised of entirely cartilaginous, standard avian anatomical elements including a concave, basin-like cricoid and fused cricoid wings. As in the larynx, both the syrinx and hyoid lack ossification and all three structures were most similar to Dromaius. We documented substantial variation across palaeognaths in the skeletal character states of the syrinx, hyoid, and larynx, using both the literature and novel observations (e.g. of C. casuarius). Notably, new synapomorphies linking Dinornithiformes and Tinamidae are identified, consistent with the molecular evidence for this clade. These shared morphological character traits include the ossification of the cricoid and arytenoid cartilages, and an additional cranial character, the articulation between the maxillary process of the nasal and the maxilla. CONCLUSION Syrinx, hyoid and larynx characters of palaeognaths display greater concordance with molecular trees than do other morphological traits. These structures might therefore be less prone to homoplasy related to flightlessness and gigantism, compared to typical morphological traits emphasised in previous phylogenetic studies.
Collapse
|
9
|
Faux C, Field DJ. Distinct developmental pathways underlie independent losses of flight in ratites. Biol Lett 2017; 13:rsbl.2017.0234. [PMID: 28679696 DOI: 10.1098/rsbl.2017.0234] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 05/30/2017] [Indexed: 12/30/2022] Open
Abstract
Recent phylogenetic studies question the monophyly of ratites (large, flightless birds incorporating ostriches, rheas, kiwis, emus and cassowaries), suggesting their paraphyly with respect to flying tinamous (Tinamidae). Flightlessness and large body size have thus likely evolved repeatedly among ratites, and separately in ostriches (Struthio) and emus (Dromaius). Here, we test this hypothesis with data from wing developmental trajectories in ostriches, emus, tinamous and chickens. We find the rate of ostrich embryonic wing growth falls within the range of variation exhibited by flying taxa (tinamous and chickens), but that of emus is extremely slow. These results indicate flightlessness was acquired by different developmental mechanisms in the ancestors of ostriches (peramorphosis) and the emu-cassowary clade (paedomorphosis), and corroborate the hypothesis that flight loss has evolved repeatedly among ratites.
Collapse
Affiliation(s)
- Cynthia Faux
- Department of Integrated Physiology and Neurosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA .,Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA
| | - Daniel J Field
- Department of Geology and Geophysics, Yale University, 210 Whitney Avenue, New Haven, CT 06511, USA .,Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, UK
| |
Collapse
|
10
|
Regnault S, Allen VR, Chadwick KP, Hutchinson JR. Analysis of the moment arms and kinematics of ostrich (Struthio camelus) double patellar sesamoids. J Exp Zool A Ecol Integr Physiol 2017; 327:163-171. [PMID: 29356388 DOI: 10.1002/jez.2082] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 06/19/2017] [Accepted: 06/26/2017] [Indexed: 02/05/2023]
Abstract
The patella ("kneecap") is a biomechanically important feature of the tendinous insertion of the knee extensor muscles, able to alter the moment arm lengths between its input and output tendons, and so modify the mechanical advantage of the knee extensor muscle. However, patellar gearing function is little-explored outside of humans, and the patella is often simplified or ignored in biomechanical models. Here, we investigate patellar gearing and kinematics in the ostrich-frequently used as an animal analogue to human bipedal locomotion and unusual in its possession of two patellae at the knee joint. We use x-ray reconstruction of moving morphology (XROMM) techniques to capture the kinematics of the patellae in an adult ostrich cadaver, passively manipulated in flexion-extension. Moment arm ratios between the input and output tendons of each patella are calculated from kinematically determined centers of patellofemoral joint rotation. Both patellae are found to decrease the mechanical advantage of the extensor muscle-tendon complex, decreasing the tendon output force for a given muscle input force, but potentially increasing the relative speed of knee extension. Mechanically and kinematically, the proximal patella behaves similarly to the single patella of most other species, whereas the distal patella has properties of both a fixed retroarticular process and a moving sesamoid. It is still not clear why ostriches possess two patellae, but we suggest that the configuration in ostriches benefits their rapid locomotion and provides tendon protection.
Collapse
Affiliation(s)
- Sophie Regnault
- Structure and Motion Laboratory, Royal Veterinary College, Hertfordshire, UK
| | - Vivian R Allen
- Structure and Motion Laboratory, Royal Veterinary College, Hertfordshire, UK
| | - Kyle P Chadwick
- Structure and Motion Laboratory, Royal Veterinary College, Hertfordshire, UK
| | - John R Hutchinson
- Structure and Motion Laboratory, Royal Veterinary College, Hertfordshire, UK
| |
Collapse
|
11
|
Regnault S, Pitsillides AA, Hutchinson JR. Structure, ontogeny and evolution of the patellar tendon in emus (Dromaius novaehollandiae) and other palaeognath birds. PeerJ 2014; 2:e711. [PMID: 25551026 PMCID: PMC4277487 DOI: 10.7717/peerj.711] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Accepted: 12/06/2014] [Indexed: 01/06/2023] Open
Abstract
The patella (kneecap) exhibits multiple evolutionary origins in birds, mammals, and lizards, and is thought to increase the mechanical advantage of the knee extensor muscles. Despite appreciable interest in the specialized anatomy and locomotion of palaeognathous birds (ratites and relatives), the structure, ontogeny and evolution of the patella in these species remains poorly characterized. Within Palaeognathae, the patella has been reported to be either present, absent, or fused with other bones, but it is unclear how much of this variation is real, erroneous or ontogenetic. Clarification of the patella’s form in palaeognaths would provide insight into the early evolution of the patella in birds, in addition to the specialized locomotion of these species. Findings would also provide new character data of use in resolving the controversial evolutionary relationships of palaeognaths. In this study, we examined the gross and histological anatomy of the emu patellar tendon across several age groups from five weeks to 18 months. We combined these results with our observations and those of others regarding the patella in palaeognaths and their outgroups (both extant and extinct), to reconstruct the evolution of the patella in birds. We found no evidence of an ossified patella in emus, but noted its tendon to have a highly unusual morphology comprising large volumes of adipose tissue contained within a collagenous meshwork. The emu patellar tendon also included increasing amounts of a cartilage-like tissue throughout ontogeny. We speculate that the unusual morphology of the patellar tendon in emus results from assimilation of a peri-articular fat pad, and metaplastic formation of cartilage, both potentially as adaptations to increasing tendon load. We corroborate previous observations of a ‘double patella’ in ostriches, but in contrast to some assertions, we find independent (i.e., unfused) ossified patellae in kiwis and tinamous. Our reconstructions suggest a single evolutionary origin of the patella in birds and that the ancestral patella is likely to have been a composite structure comprising a small ossified portion, lost by some species (e.g., emus, moa) but expanded in others (e.g., ostriches).
Collapse
Affiliation(s)
- Sophie Regnault
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College , Hatfield , United Kingdom
| | - Andrew A Pitsillides
- Department of Comparative Biomedical Sciences, The Royal Veterinary College , London , United Kingdom
| | - John R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College , Hatfield , United Kingdom
| |
Collapse
|
12
|
Lamas LP, Main RP, Hutchinson JR. Ontogenetic scaling patterns and functional anatomy of the pelvic limb musculature in emus (Dromaius novaehollandiae). PeerJ 2014; 2:e716. [PMID: 25551028 PMCID: PMC4277488 DOI: 10.7717/peerj.716] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 12/10/2014] [Indexed: 11/30/2022] Open
Abstract
Emus (Dromaius novaehollandiae) are exclusively terrestrial, bipedal and cursorial ratites with some similar biomechanical characteristics to humans. Their growth rates are impressive, as their body mass increases eighty-fold from hatching to adulthood whilst maintaining the same mode of locomotion throughout life. These ontogenetic characteristics stimulate biomechanical questions about the strategies that allow emus to cope with their rapid growth and locomotion, which can be partly addressed via scaling (allometric) analysis of morphology. In this study we have collected pelvic limb anatomical data (muscle architecture, tendon length, tendon mass and bone lengths) and calculated muscle physiological cross sectional area (PCSA) and average tendon cross sectional area from emus across three ontogenetic stages (n = 17, body masses from 3.6 to 42 kg). The data were analysed by reduced major axis regression to determine how these biomechanically relevant aspects of morphology scaled with body mass. Muscle mass and PCSA showed a marked trend towards positive allometry (26 and 27 out of 34 muscles respectively) and fascicle length showed a more mixed scaling pattern. The long tendons of the main digital flexors scaled with positive allometry for all characteristics whilst other tendons demonstrated a less clear scaling pattern. Finally, the two longer bones of the limb (tibiotarsus and tarsometatarsus) also exhibited positive allometry for length, and two others (femur and first phalanx of digit III) had trends towards isometry. These results indicate that emus experience a relative increase in their muscle force-generating capacities, as well as potentially increasing the force-sustaining capacities of their tendons, as they grow. Furthermore, we have clarified anatomical descriptions and provided illustrations of the pelvic limb muscle–tendon units in emus.
Collapse
Affiliation(s)
- Luis P Lamas
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College , Hatfield , United Kingdom
| | - Russell P Main
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University , West Lafayette, IN , USA
| | - John R Hutchinson
- Structure and Motion Laboratory, Department of Comparative Biomedical Sciences, The Royal Veterinary College , Hatfield , United Kingdom
| |
Collapse
|