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A new archosauriform (Reptilia: Diapsida) from the Manda beds (Middle Triassic) of southwestern Tanzania.
PLoS One. 2013; 8(9):e72753.Plos

Abstract

BACKGROUND

Archosauria and their closest relatives, the non-archosaurian archosauriforms, diversified in the Early and Middle Triassic, soon after the end-Permian extinction. This diversification is poorly documented in most Lower and Middle Triassic rock sequences because fossils of early groups of archosauriforms are relatively rare compared to those of other amniotes. The early Middle Triassic (? late Anisian) Manda beds of southwestern Tanzania form an exception, with early archosaur skeletons being relatively common and preserved as articulated or associated specimens. The Manda archosaur assemblage is exceptionally diverse for the Middle Triassic. However, to date, no non-archosaurian archosauriforms have been reported from these rocks.

METHODOLOGY/PRINCIPAL FINDINGS

Here, we name a new taxon, Asperoris mnyama gen. et sp. nov., from the Manda beds and thoroughly describe the only known specimen. The specimen consists of a well-preserved partial skull including tooth-bearing elements (premaxilla, maxilla), the nasal, partial skull roof, and several incomplete elements. All skull elements are covered in an autapomorphic highly rugose sculpturing. A unique combination of character states indicates that A. mnyama lies just outside Archosauria as a stem archosaur within Archosauriformes, but more precise relationships of A. mnyama relative to other early archosauriform clades (e.g., Erythrosuchidae) cannot be determined currently.

CONCLUSIONS/SIGNIFICANCE

Asperoris mnyama is the first confirmed non-archosaurian archosauriform from the Manda beds and increases the morphological and taxonomic diversity of early archosauriforms known from the Middle Triassic. The direct association of A. mnyama with species referable to Archosauria demonstrates that non-archosaurian archosauriforms were present during the rise and early diversification of Archosauria. Non-archosaurian archosauriforms and archosaurs co-occur in fossil reptile assemblages across Pangaea from the late Early Triassic to the end of the Late Triassic.

Authors+Show Affiliations

Burke Museum and Department of Biology, University of Washington, Seattle, Washington, United States of America.No affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

24086264

Citation

Nesbitt, Sterling J., et al. "A New Archosauriform (Reptilia: Diapsida) From the Manda Beds (Middle Triassic) of Southwestern Tanzania." PloS One, vol. 8, no. 9, 2013, pp. e72753.
Nesbitt SJ, Butler RJ, Gower DJ. A new archosauriform (Reptilia: Diapsida) from the Manda beds (Middle Triassic) of southwestern Tanzania. PLoS One. 2013;8(9):e72753.
Nesbitt, S. J., Butler, R. J., & Gower, D. J. (2013). A new archosauriform (Reptilia: Diapsida) from the Manda beds (Middle Triassic) of southwestern Tanzania. PloS One, 8(9), e72753. https://doi.org/10.1371/journal.pone.0072753
Nesbitt SJ, Butler RJ, Gower DJ. A New Archosauriform (Reptilia: Diapsida) From the Manda Beds (Middle Triassic) of Southwestern Tanzania. PLoS One. 2013;8(9):e72753. PubMed PMID: 24086264.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A new archosauriform (Reptilia: Diapsida) from the Manda beds (Middle Triassic) of southwestern Tanzania. AU - Nesbitt,Sterling J, AU - Butler,Richard J, AU - Gower,David J, Y1 - 2013/09/27/ PY - 2013/02/05/received PY - 2013/07/05/accepted PY - 2013/10/3/entrez PY - 2013/10/3/pubmed PY - 2014/7/19/medline SP - e72753 EP - e72753 JF - PloS one JO - PLoS One VL - 8 IS - 9 N2 - BACKGROUND: Archosauria and their closest relatives, the non-archosaurian archosauriforms, diversified in the Early and Middle Triassic, soon after the end-Permian extinction. This diversification is poorly documented in most Lower and Middle Triassic rock sequences because fossils of early groups of archosauriforms are relatively rare compared to those of other amniotes. The early Middle Triassic (? late Anisian) Manda beds of southwestern Tanzania form an exception, with early archosaur skeletons being relatively common and preserved as articulated or associated specimens. The Manda archosaur assemblage is exceptionally diverse for the Middle Triassic. However, to date, no non-archosaurian archosauriforms have been reported from these rocks. METHODOLOGY/PRINCIPAL FINDINGS: Here, we name a new taxon, Asperoris mnyama gen. et sp. nov., from the Manda beds and thoroughly describe the only known specimen. The specimen consists of a well-preserved partial skull including tooth-bearing elements (premaxilla, maxilla), the nasal, partial skull roof, and several incomplete elements. All skull elements are covered in an autapomorphic highly rugose sculpturing. A unique combination of character states indicates that A. mnyama lies just outside Archosauria as a stem archosaur within Archosauriformes, but more precise relationships of A. mnyama relative to other early archosauriform clades (e.g., Erythrosuchidae) cannot be determined currently. CONCLUSIONS/SIGNIFICANCE: Asperoris mnyama is the first confirmed non-archosaurian archosauriform from the Manda beds and increases the morphological and taxonomic diversity of early archosauriforms known from the Middle Triassic. The direct association of A. mnyama with species referable to Archosauria demonstrates that non-archosaurian archosauriforms were present during the rise and early diversification of Archosauria. Non-archosaurian archosauriforms and archosaurs co-occur in fossil reptile assemblages across Pangaea from the late Early Triassic to the end of the Late Triassic. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/24086264/A_new_archosauriform__Reptilia:_Diapsida__from_the_Manda_beds__Middle_Triassic__of_southwestern_Tanzania_ L2 - https://dx.plos.org/10.1371/journal.pone.0072753 DB - PRIME DP - Unbound Medicine ER -
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