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Tagliavento M, Davies AJ, Bernecker M, Staudigel PT, Dawson RR, Dietzel M, Götschl K, Guo W, Schulp AS, Therrien F, Zelenitsky DK, Gerdes A, Müller W, Fiebig J. Evidence for heterothermic endothermy and reptile-like eggshell mineralization in Troodon, a non-avian maniraptoran theropod. Proc Natl Acad Sci U S A 2023; 120:e2213987120. [PMID: 37011196 PMCID: PMC10104568 DOI: 10.1073/pnas.2213987120] [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: 08/15/2022] [Accepted: 02/15/2023] [Indexed: 04/05/2023] Open
Abstract
The dinosaur-bird transition involved several anatomical, biomechanical, and physiological modifications of the theropod bauplan. Non-avian maniraptoran theropods, such as Troodon, are key to better understand changes in thermophysiology and reproduction occurring during this transition. Here, we applied dual clumped isotope (Δ47 and Δ48) thermometry, a technique that resolves mineralization temperature and other nonthermal information recorded in carbonates, to eggshells from Troodon, modern reptiles, and modern birds. Troodon eggshells show variable temperatures, namely 42 and 29 ± 2 °C, supporting the hypothesis of an endothermic thermophysiology with a heterothermic strategy for this extinct taxon. Dual clumped isotope data also reveal physiological differences in the reproductive systems between Troodon, reptiles, and birds. Troodon and modern reptiles mineralize their eggshells indistinguishable from dual clumped isotope equilibrium, while birds precipitate eggshells characterized by a positive disequilibrium offset in Δ48. Analyses of inorganic calcites suggest that the observed disequilibrium pattern in birds is linked to an amorphous calcium carbonate (ACC) precursor, a carbonate phase known to accelerate eggshell formation in birds. Lack of disequilibrium patterns in reptile and Troodon eggshells implies these vertebrates had not acquired the fast, ACC-based eggshell calcification process characteristic of birds. Observation that Troodon retained a slow reptile-like calcification suggests that it possessed two functional ovaries and was limited in the number of eggs it could produce; thus its large clutches would have been laid by several females. Dual clumped isotope analysis of eggshells of extinct vertebrates sheds light on physiological information otherwise inaccessible in the fossil record.
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Affiliation(s)
- Mattia Tagliavento
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Amelia J. Davies
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Miguel Bernecker
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Philip T. Staudigel
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Robin R. Dawson
- Department of Earth, Geographic and Climate Sciences, University of Massachusetts, Amherst, MA01003
| | - Martin Dietzel
- Institute of Applied Geosciences, Graz University of Technology,8010Graz, Austria
| | - Katja Götschl
- Institute of Applied Geosciences, Graz University of Technology,8010Graz, Austria
| | - Weifu Guo
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA02543
| | - Anne S. Schulp
- Vertebrate Evolution and Development, Naturalis Biodiversity Center,2333CRLeiden, the Netherlands
- Department of Earth Sciences, Faculty of Geosciences, Universiteit Utrecht,3584 CBUtrecht, the Netherlands
| | | | | | - Axel Gerdes
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
- Frankfurt Isotope and Element Research Center, Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Wolfgang Müller
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
- Frankfurt Isotope and Element Research Center, Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
| | - Jens Fiebig
- Institute of Geosciences, Goethe University Frankfurt, Frankfurt am Main60438, Germany
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Cincotta A, Nicolaï M, Campos HBN, McNamara M, D'Alba L, Shawkey MD, Kischlat EE, Yans J, Carleer R, Escuillié F, Godefroit P. Pterosaur melanosomes support signalling functions for early feathers. Nature 2022; 604:684-688. [PMID: 35444275 PMCID: PMC9046085 DOI: 10.1038/s41586-022-04622-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 03/07/2022] [Indexed: 01/10/2023]
Abstract
Remarkably well-preserved soft tissues in Mesozoic fossils have yielded substantial insights into the evolution of feathers1. New evidence of branched feathers in pterosaurs suggests that feathers originated in the avemetatarsalian ancestor of pterosaurs and dinosaurs in the Early Triassic2, but the homology of these pterosaur structures with feathers is controversial3,4. Reports of pterosaur feathers with homogeneous ovoid melanosome geometries2,5 suggest that they exhibited limited variation in colour, supporting hypotheses that early feathers functioned primarily in thermoregulation6. Here we report the presence of diverse melanosome geometries in the skin and simple and branched feathers of a tapejarid pterosaur from the Early Cretaceous found in Brazil. The melanosomes form distinct populations in different feather types and the skin, a feature previously known only in theropod dinosaurs, including birds. These tissue-specific melanosome geometries in pterosaurs indicate that manipulation of feather colour-and thus functions of feathers in visual communication-has deep evolutionary origins. These features show that genetic regulation of melanosome chemistry and shape7-9 was active early in feather evolution.
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Affiliation(s)
- Aude Cincotta
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium. .,Institute of Life, Earth and Environment, University of Namur, Namur, Belgium. .,School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland. .,Environmental Research Institute, University College Cork, Cork, Ireland.
| | - Michaël Nicolaï
- Evolution and Optics of Nanostructures Group, Biology Department, Ghent University, Ghent, Belgium
| | | | - Maria McNamara
- School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland. .,Environmental Research Institute, University College Cork, Cork, Ireland.
| | - Liliana D'Alba
- Evolution and Optics of Nanostructures Group, Biology Department, Ghent University, Ghent, Belgium.,Naturalis Biodiversity Center, Leiden, The Netherlands
| | - Matthew D Shawkey
- Evolution and Optics of Nanostructures Group, Biology Department, Ghent University, Ghent, Belgium
| | - Edio-Ernst Kischlat
- Divisão de Bacias Sedimentares, Geological Survey of Brazil, Porto Alegre, Brazil
| | - Johan Yans
- Institute of Life, Earth and Environment, University of Namur, Namur, Belgium
| | - Robert Carleer
- Research Group of Analytical and Circular Chemistry, Institute for Material Research, Hasselt University, Diepenbeek, Belgium
| | | | - Pascal Godefroit
- Directorate Earth and History of Life, Royal Belgian Institute of Natural Sciences, Brussels, Belgium
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Hendrickx C, Bell PR, Pittman M, Milner ARC, Cuesta E, O'Connor J, Loewen M, Currie PJ, Mateus O, Kaye TG, Delcourt R. Morphology and distribution of scales, dermal ossifications, and other non-feather integumentary structures in non-avialan theropod dinosaurs. Biol Rev Camb Philos Soc 2022; 97:960-1004. [PMID: 34991180 DOI: 10.1111/brv.12829] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/10/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022]
Abstract
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.
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Affiliation(s)
- Christophe Hendrickx
- Unidad Ejecutora Lillo, CONICET-Fundación Miguel Lillo, 251 Miguel Lillo, San Miguel de Tucumán, Tucumán, 4000, Argentina
| | - Phil R Bell
- School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia
| | - Michael Pittman
- Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong, Pokfulam, Hong Kong, SAR, China.,Department of Earth Sciences, University College London, WC1E 6BT, United Kingdom
| | - Andrew R C Milner
- St. George Dinosaur Discovery Site at Johnson Farm, 2180 East Riverside Drive, St. George, UT, U.S.A
| | - Elena Cuesta
- Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, Munich, 80333, Germany
| | - Jingmai O'Connor
- Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL, 60605, U.S.A
| | - Mark Loewen
- Department of Geology and Geophysics, University of Utah, Frederick Albert Sutton Building, 115 South 1460 East, Salt Lake City, UT, 84112, U.S.A.,Natural History Museum of Utah, 301 Wakara Way, Salt Lake City, UT, 84108, U.S.A
| | - Philip J Currie
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Octávio Mateus
- GeoBioTec, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal.,Museu da Lourinhã, 95 Rua João Luis de Moura, Lourinhã, 2530-158, Portugal
| | - Thomas G Kaye
- Foundation for Scientific Advancement, 7023 Alhambra Dr., Sierra Vista, AZ, 85650, U.S.A
| | - Rafael Delcourt
- Universidade Estadual de Campinas (UNICAMP), Instituto de Geociências, Cidade Universitária, Rua Carlos Gomes, 250, Campinas, SP, 13083-855, Brazil
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