Deep evolutionary diversification of semicircular canals in archosaurs

Author(s):Show less -

Bronzati, Mario ^[1] ; Benson, Roger B. J. ^{[2, 3]} ; Evers, Serjoscha W. ^{[2, 4]} ; Ezcurra, Martin D. ^{[5, 6]} ; Cabreira, Sergio F. ^[7] ; Choiniere, Jonah ^[3] ; Dollman, Kathleen N. ^[3] ; Paulina-Carabajal, Ariana ^[8] ; Radermacher, Viktor J. ^[3] ; Roberto-da-Silva, Lucio ^[9] ; Sobral, Gabriela ^[10] ; Stocker, Michelle R. ^[11] ; Witmer, Lawrence M. ^[12] ; Langer, Max C. ^[1] ; Nesbitt, Sterling J. ^[11]

Affiliation:Show less -

^[1] Univ Sao Paulo, Dept Biol, Ave Bandeirantes 1900, BR-14040091 Ribeirao Preto, SP - Brazil

^[2] Univ Oxford, Dept Earth Sci, South Parks Rd, Oxford OX13AN - England

^[3] Univ Witwatersrand, Evolutionary Studies Inst, Private Bag 3, ZA-2050 Johannesburg - South Africa

^[4] Univ Fribourg, Dept Geosci, Chemin Musee 4, CH-1700 Fribourg - Switzerland

^[5] Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands - England

^[6] CONICET Museo Argentino Ciencias Nat Bernardino R, Secc Paleontol Vertebrados, Angel Gallardo 470, C1405DJR, Buenos Aires, DF - Argentina

^[7] Ave Antonio Bozzetto 305, BR-97220000 Faxinal Do Soturno, RS - Brazil

^[8] CONICET Univ Nacl Comahue, Inst Invest Biodiversidad & Medioambiente INIBIOM, RA-8400 San Carlos De Bariloche, Rio Negro - Argentina

^[9] Rua Venancio Trindade 810, BR-96506290 Cachoeira Do Sul, RS - Brazil

^[10] Staatliches Museum Nat Kunde Stuttgart, Rosenstein 1, D-70191 Stuttgart - Germany

^[11] Virginia Tech, Dept Geosci, 926 West Campus Dr, Blacksburg, VA 24061 - USA

^[12] Ohio Univ, Heritage Coll Osteopath Med, Dept Biomed Sci, Athens, OH 45701 - USA

• Document type: Journal article
• Source: Current Biology; v. 31, n. 12, p. 2520+, JUN 21 2021.
• Web of Science Citations: 1

Abstract

Living archosaurs (birds and crocodylians) have disparate locomotor strategies that evolved since their divergence-250 mya. Little is known about the early evolution of the sensory structures that are coupled with these changes, mostly due to limited sampling of early fossils on key stem lineages. In particular, the morphology of the semicircular canals (SCCs) of the endosseous labyrinth has a long-hypothesized relationship with locomotion. Here, we analyze SCC shapes and sizes of living and extinct archosaurs encompassing diverse locomotor habits, including bipedal, semi-aquatic, and flying taxa. We test form-function hypotheses of the SCCs and chronicle their evolution during deep archosaurian divergences. We find that SCC shape is statistically associated with both flight and bipedalism. However, this shape variation is small and is more likely explained by changes in braincase geometry than by locomotor changes. We demonstrate high disparity of both shape and size among stem-archosaurs and a deep divergence of SCC morphologies at the bird-crocodylian split. Stem-crocodylians exhibit diverse morphologies, including aspects also present in birds and distinct from other reptiles. Therefore, extant crocodylian SCC morphologies do not reflect retention of a ``primitive{''}reptilian condition. Key aspects of bird SCC morphology that hitherto were interpreted as flight related, including large SCC size and enhanced sensitivity, appeared early on the bird stem-lineage in non-flying dinosaur precursors. Taken together, our results indicate a deep divergence of SCC traits at the bird-crocodylian split and that living archosaurs evolved from an early radiation with high sensory diversity. (AU)

• FAPESP's process: 18/18145-9 - INTEGRATING EVO-DEVO AND PALAEONTOLOGY ON THE STUDY OF THE ORIGIN AND EVOLUTION OF THE TYMPANIC MEMBRANE IN DIAPSIDA
• Grantee: Mario Bronzati Filho
• Support type: Scholarships in Brazil - Post-Doctorate
• FAPESP's process: 14/03825-3 - The origin and rise of dinosaurs in Gondwana (late Triassic - early Jurassic)
• Grantee: Max Cardoso Langer
• Support type: Research Projects - Thematic Grants