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The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation.
PLoS One. 2011; 6(10):e25693.Plos

Abstract

BACKGROUND

Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3-247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains.

METHODOLOGY/PRINCIPAL FINDINGS

We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the 'sail' of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation.

CONCLUSIONS/SIGNIFICANCE

Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian-Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs.

Authors+Show Affiliations

Bayerische Staatssammlung für Paläontologie und Geologie, München, Germany. r.butler@lrz.uni-muenchen.deNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

22022431

Citation

Butler, Richard J., et al. "The Sail-backed Reptile Ctenosauriscus From the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation." PloS One, vol. 6, no. 10, 2011, pp. e25693.
Butler RJ, Brusatte SL, Reich M, et al. The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation. PLoS One. 2011;6(10):e25693.
Butler, R. J., Brusatte, S. L., Reich, M., Nesbitt, S. J., Schoch, R. R., & Hornung, J. J. (2011). The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation. PloS One, 6(10), e25693. https://doi.org/10.1371/journal.pone.0025693
Butler RJ, et al. The Sail-backed Reptile Ctenosauriscus From the Latest Early Triassic of Germany and the Timing and Biogeography of the Early Archosaur Radiation. PLoS One. 2011;6(10):e25693. PubMed PMID: 22022431.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The sail-backed reptile Ctenosauriscus from the latest Early Triassic of Germany and the timing and biogeography of the early archosaur radiation. AU - Butler,Richard J, AU - Brusatte,Stephen L, AU - Reich,Mike, AU - Nesbitt,Sterling J, AU - Schoch,Rainer R, AU - Hornung,Jahn J, Y1 - 2011/10/14/ PY - 2011/08/17/received PY - 2011/09/08/accepted PY - 2011/10/25/entrez PY - 2011/10/25/pubmed PY - 2012/2/18/medline SP - e25693 EP - e25693 JF - PloS one JO - PLoS One VL - 6 IS - 10 N2 - BACKGROUND: Archosaurs (birds, crocodilians and their extinct relatives including dinosaurs) dominated Mesozoic continental ecosystems from the Late Triassic onwards, and still form a major component of modern ecosystems (>10,000 species). The earliest diverse archosaur faunal assemblages are known from the Middle Triassic (c. 244 Ma), implying that the archosaur radiation began in the Early Triassic (252.3-247.2 Ma). Understanding of this radiation is currently limited by the poor early fossil record of the group in terms of skeletal remains. METHODOLOGY/PRINCIPAL FINDINGS: We redescribe the anatomy and stratigraphic position of the type specimen of Ctenosauriscus koeneni (Huene), a sail-backed reptile from the Early Triassic (late Olenekian) Solling Formation of northern Germany that potentially represents the oldest known archosaur. We critically discuss previous biomechanical work on the 'sail' of Ctenosauriscus, which is formed by a series of elongated neural spines. In addition, we describe Ctenosauriscus-like postcranial material from the earliest Middle Triassic (early Anisian) Röt Formation of Waldhaus, southwestern Germany. Finally, we review the spatial and temporal distribution of the earliest archosaur fossils and their implications for understanding the dynamics of the archosaur radiation. CONCLUSIONS/SIGNIFICANCE: Comprehensive numerical phylogenetic analyses demonstrate that both Ctenosauriscus and the Waldhaus taxon are members of a monophyletic grouping of poposauroid archosaurs, Ctenosauriscidae, characterised by greatly elongated neural spines in the posterior cervical to anterior caudal vertebrae. The earliest archosaurs, including Ctenosauriscus, appear in the body fossil record just prior to the Olenekian/Anisian boundary (c. 248 Ma), less than 5 million years after the Permian-Triassic mass extinction. These earliest archosaur assemblages are dominated by ctenosauriscids, which were broadly distributed across northern Pangea and which appear to have been the first global radiation of archosaurs. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/22022431/The_sail_backed_reptile_Ctenosauriscus_from_the_latest_Early_Triassic_of_Germany_and_the_timing_and_biogeography_of_the_early_archosaur_radiation_ L2 - https://dx.plos.org/10.1371/journal.pone.0025693 DB - PRIME DP - Unbound Medicine ER -