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A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America.
PLoS One. 2011; 6(9):e24487.Plos

Abstract

BACKGROUND

Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains.

METHODOLOGY/PRINCIPAL FINDINGS

Here we report a gracile new troodontid theropod--Talos sampsoni gen. et sp. nov.--from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes.

CONCLUSION/SIGNIFICANCE

Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing.

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Authors+Show Affiliations

Zanno LE
Field Museum of Natural History, Chicago, Illinois, United States of America. lzanno@fieldmuseum.org
Varricchio DJ
No affiliation info available
O'Connor PM
No affiliation info available
Titus AL
No affiliation info available
Knell MJ
No affiliation info available

MeSH

AnimalsBone and BonesDinosaursNorth AmericaPaleontologyPhylogenyX-Ray Microtomography

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

21949721

Citation

Zanno, Lindsay E., et al. "A New Troodontid Theropod, Talos Sampsoni Gen. Et Sp. Nov., From the Upper Cretaceous Western Interior Basin of North America." PloS One, vol. 6, no. 9, 2011, pp. e24487.
Zanno LE, Varricchio DJ, O'Connor PM, et al. A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America. PLoS One. 2011;6(9):e24487.
Zanno, L. E., Varricchio, D. J., O'Connor, P. M., Titus, A. L., & Knell, M. J. (2011). A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America. PloS One, 6(9), e24487. https://doi.org/10.1371/journal.pone.0024487
Zanno LE, et al. A New Troodontid Theropod, Talos Sampsoni Gen. Et Sp. Nov., From the Upper Cretaceous Western Interior Basin of North America. PLoS One. 2011;6(9):e24487. PubMed PMID: 21949721.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A new troodontid theropod, Talos sampsoni gen. et sp. nov., from the Upper Cretaceous Western Interior Basin of North America. AU - Zanno,Lindsay E, AU - Varricchio,David J, AU - O'Connor,Patrick M, AU - Titus,Alan L, AU - Knell,Michael J, Y1 - 2011/09/19/ PY - 2011/05/16/received PY - 2011/08/11/accepted PY - 2011/9/28/entrez PY - 2011/9/29/pubmed PY - 2012/2/4/medline SP - e24487 EP - e24487 JF - PloS one JO - PLoS One VL - 6 IS - 9 N2 - BACKGROUND: Troodontids are a predominantly small-bodied group of feathered theropod dinosaurs notable for their close evolutionary relationship with Avialae. Despite a diverse Asian representation with remarkable growth in recent years, the North American record of the clade remains poor, with only one controversial species--Troodon formosus--presently known from substantial skeletal remains. METHODOLOGY/PRINCIPAL FINDINGS: Here we report a gracile new troodontid theropod--Talos sampsoni gen. et sp. nov.--from the Upper Cretaceous Kaiparowits Formation, Utah, USA, representing one of the most complete troodontid skeletons described from North America to date. Histological assessment of the holotype specimen indicates that the adult body size of Talos was notably smaller than that of the contemporary genus Troodon. Phylogenetic analysis recovers Talos as a member of a derived, latest Cretaceous subclade, minimally containing Troodon, Saurornithoides, and Zanabazar. MicroCT scans reveal extreme pathological remodeling on pedal phalanx II-1 of the holotype specimen likely resulting from physical trauma and subsequent infectious processes. CONCLUSION/SIGNIFICANCE: Talos sampsoni adds to the singularity of the Kaiparowits Formation dinosaur fauna, which is represented by at least 10 previously unrecognized species including the recently named ceratopsids Utahceratops and Kosmoceratops, the hadrosaurine Gryposaurus monumentensis, the tyrannosaurid Teratophoneus, and the oviraptorosaurian Hagryphus. The presence of a distinct troodontid taxon in the Kaiparowits Formation supports the hypothesis that late Campanian dinosaurs of the Western Interior Basin exhibited restricted geographic ranges and suggests that the taxonomic diversity of Late Cretaceous troodontids from North America is currently underestimated. An apparent traumatic injury to the foot of Talos with evidence of subsequent healing sheds new light on the paleobiology of deinonychosaurians by bolstering functional interpretations of prey grappling and/or intraspecific combat for the second pedal digit, and supporting trackway evidence indicating a minimal role in weight bearing. SN - 1932-6203 UR - https://www.unboundmedicine.com/medline/citation/21949721/A_new_troodontid_theropod_Talos_sampsoni_gen__et_sp__nov__from_the_Upper_Cretaceous_Western_Interior_Basin_of_North_America_ L2 - https://dx.plos.org/10.1371/journal.pone.0024487 DB - PRIME DP - Unbound Medicine ER -