Aerodynamics Show Membranous-Winged Theropods Were a Poor Gliding Dead-End

Dececchi, T. Alexander; Roy, Arindam; Pittman, Michael; Kaye, Thomas G.; Xu, Xing; Habib, Michael B.; Larsson, Hans C. E.; Wang, Xiaoli; Zheng, Xiaoting

doi:10.2139/ssrn.3640840

Cited by 2 publications

(5 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other than the tail, the integument of the neck is also relatively well represented (Fig. 17), being preserved in six non‐avialan averostrans: the allosauroids Allosaurus and Concavenator (Appendix S3.4), the tyrannosaurid Tyrannosaurus (Bell et al ., 2017), the ornithomimosaurian Pelecanimimus (Pérez‐Moreno et al ., 1994; Briggs et al ., 1997), the scansoriopterygid Yi (Dececchi et al ., 2020), and the dromaeosaurid Microraptor (Hone et al ., 2010). The skin appears to be scaleless at least in its ventral part in Pelecanimimus (Briggs et al ., 1997) and Concavenator , whereas it is made of small polygonal scales in Tyrannosaurus (Bell et al ., 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Dececchi et al . (2020) revealed soft tissues around the head of the scansoriopterygid Yi qi under LSF. However, these are not sufficiently well preserved to discern their textural details.…”

Section: Discussionmentioning

confidence: 99%

“…Carpenter (1997) also reported the presence of a wattle or bag of skin under the jaws of a badly weathered skull of Tarbosaurus from Mongolia, although such claims have not been validated (see Section V.1d). Dececchi et al (2020) revealed soft tissues around the head of the scansoriopterygid Yi qi under LSF. However, these are not sufficiently well preserved to discern their textural details.…”

Section: Discussionmentioning

confidence: 99%

“…One of the most unusual integumentary structures discovered in recent years pertain to the enigmatic scansoriopterygids, once again from China. At least two genera, Yi and Ambopteryx , appear to show bare‐skin membranes stretched between hypertrophied manual digits and a rod‐like styliform element (Xu et al ., 2015; Wang et al ., 2019), representing an entirely novel theropod flight architecture and demonstrating the role of integument in forming unprecedented structures (Dececchi et al ., 2020).…”

Section: Historical Overview Of Theropod Integumentary Discoveries (I...mentioning

confidence: 99%

See 3 more Smart Citations

Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs

et al. 2022

Self Cite

View full text Add to dashboard Cite

Modern birds are typified by the presence of feathers, complex evolutionary innovations that were already widespread in the group of theropod dinosaurs (Maniraptoriformes) that include crown Aves. Squamous or scaly reptilian‐like skin is, however, considered the plesiomorphic condition for theropods and dinosaurs more broadly. Here, we review the morphology and distribution of non‐feathered integumentary structures in non‐avialan theropods, covering squamous skin and naked skin as well as dermal ossifications. The integumentary record of non‐averostran theropods is limited to tracks, which ubiquitously show a covering of tiny reticulate scales on the plantar surface of the pes. This is consistent also with younger averostran body fossils, which confirm an arthral arrangement of the digital pads. Among averostrans, squamous skin is confirmed in Ceratosauria (Carnotaurus), Allosauroidea (Allosaurus, Concavenator, Lourinhanosaurus), Compsognathidae (Juravenator), and Tyrannosauroidea (Santanaraptor, Albertosaurus, Daspletosaurus, Gorgosaurus, Tarbosaurus, Tyrannosaurus), whereas dermal ossifications consisting of sagittate and mosaic osteoderms are restricted to Ceratosaurus. Naked, non‐scale bearing skin is found in the contentious tetanuran Sciurumimus, ornithomimosaurians (Ornithomimus) and possibly tyrannosauroids (Santanaraptor), and also on the patagia of scansoriopterygids (Ambopteryx, Yi). Scales are surprisingly conservative among non‐avialan theropods compared to some dinosaurian groups (e.g. hadrosaurids); however, the limited preservation of tegument on most specimens hinders further interrogation. Scale patterns vary among and/or within body regions in Carnotaurus, Concavenator and Juravenator, and include polarised, snake‐like ventral scales on the tail of the latter two genera. Unusual but more uniformly distributed patterning also occurs in Tyrannosaurus, whereas feature scales are present only in Albertosaurus and Carnotaurus. Few theropods currently show compelling evidence for the co‐occurrence of scales and feathers (e.g. Juravenator, Sinornithosaurus), although reticulate scales were probably retained on the mani and pedes of many theropods with a heavy plumage. Feathers and filamentous structures appear to have replaced widespread scaly integuments in maniraptorans. Theropod skin, and that of dinosaurs more broadly, remains a virtually untapped area of study and the appropriation of commonly used techniques in other palaeontological fields to the study of skin holds great promise for future insights into the biology, taphonomy and relationships of these extinct animals.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Historical Overview Of Theropod Integumentary Discoveries (I...mentioning

confidence: 99%

See 2 more Smart Citations

Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The scansoriopterygids [possibly early‐diverging avialans or non‐avialan pennaraptorans (Pittman et al ., 2020 a )] Epidexipteryx and Yi appear adapted for carnivory due to low values of mechanical advantage and most of the functional indices recommended herein (Ma et al ., 2020). Body mass estimates above 300 g in Yi (Dececchi et al ., 2020) specifically point to it being a vertivore. To our knowledge, no quantitative study of anchiornithine [possibly early‐diverging avialans or troodontids (Pittman et al ., 2020 a )] diet has been performed.…”

Section: The Framework and Current Knowledge Of Non‐avian Avialan Dietmentioning

confidence: 99%

The diet of early birds based on modern and fossil evidence and a new framework for its reconstruction

Miller

Pittman

2021

Biological Reviews

Self Cite

View full text Add to dashboard Cite

Birds are some of the most diverse organisms on Earth, with species inhabiting a wide variety of niches across every major biome. As such, birds are vital to our understanding of modern ecosystems. Unfortunately, our understanding of the evolutionary history of modern ecosystems is hampered by knowledge gaps in the origin of modern bird diversity and ecosystem ecology. A crucial part of addressing these shortcomings is improving our understanding of the earliest birds, the non-avian avialans (i.e. non-crown birds), particularly of their diet. The diet of non-avian avialans has been a matter of debate, in large part because of the ambiguous qualitative approaches that have been used to reconstruct it. Here we review methods for determining diet in modern and fossil avians (i.e. crown birds) as well as non-avian theropods, and comment on their usefulness when applied to non-avian avialans. We use this to propose a set of comparable, quantitative approaches to ascertain fossil bird diet and on this basis provide a consensus of what we currently know about fossil bird diet. While no single approach can precisely predict diet in birds, each can exclude some diets and narrow the dietary possibilities. We recommend combining (i) dental microwear, (ii) landmark-based muscular reconstruction, (iii) stable isotope geochemistry, (iv) body mass estimations, (v) traditional and/or geometric morphometric analysis, (vi) lever modelling, and (vii) finite element analysis to reconstruct fossil bird diet accurately. Our review provides specific methodologies to implement each approach and discusses complications future researchers should keep in mind. We note that current forms of assessment of dental mesowear, skull traditional morphometrics, geometric morphometrics, and certain stable isotope systems have yet to be proven effective at discerning fossil bird diet. On this basis we report the current state of knowledge of non-avian avialan diet which remains very incomplete. The ancestral dietary condition in non-avian avialans remains unclear due to scarce data and contradictory evidence in Archaeopteryx. Among early non-avian pygostylians, Confuciusornis has finite element analysis and mechanical advantage evidence pointing to herbivory, whilst Sapeornis only has mechanical advantage evidence indicating granivory, agreeing with fossilised ingested material known for this taxon. The enantiornithine ornithothoracine Shenqiornis has mechanical advantage and pedal morphometric evidence pointing to carnivory. In the hongshanornithid ornithuromorph Hongshanornis only mechanical advantage evidence indicates granivory, but this agrees with evidence of gastrolith ingestion in this taxon. Mechanical advantage and ingested fish support carnivory in the songlingornithid ornithuromorph Yanornis. Due to the sparsity of robust dietary assignments, no clear trends in non-avian avialan dietary evolution have yet emerged. Dietary diversity seems to increase through time, but this is a preservational bias associated with a predominance of data fro...

show abstract

Aerodynamics Show Membranous-Winged Theropods Were a Poor Gliding Dead-End

Cited by 2 publications

References 35 publications

Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs

Morphology and distribution of scales, dermal ossifications, and other non‐feather integumentary structures in non‐avialan theropod dinosaurs

The diet of early birds based on modern and fossil evidence and a new framework for its reconstruction

Contact Info

Product

Resources

About