scholarly journals Magnetostratigraphy of the Upper Triassic Chinle Group of New Mexico: Implications for regional and global correlations among Upper Triassic sequences

Geosphere ◽  
2011 ◽  
Vol 7 (3) ◽  
pp. 802-829 ◽  
Author(s):  
Kate E. Zeigler ◽  
John W. Geissman
Keyword(s):  
New Mexico ◽  
Upper Triassic ◽  
Chinle Group

Grallator-Dominated Fossil Footprint Assemblages and Associated Enigmatic Footprints from the Chinle Group (Upper Triassic), Gateway Area, Colorado

Ichnos ◽  
2003 ◽  
Vol 10 (2-4) ◽  
pp. 153-163 ◽  
Author(s):  
Robert Gaston ◽  
Martin Lockley ◽  
Spencer Lucas ◽  
Adrian Hunt
Keyword(s):  
Upper Triassic ◽  
Chinle Group

scholarly journals A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell

2008 ◽  
Vol 276 (1656) ◽  
pp. 507-513 ◽  
Author(s):  
Walter G Joyce ◽  
Spencer G Lucas ◽  
Torsten M Scheyer ◽  
Andrew B Heckert ◽  
Adrian P Hunt
Keyword(s):  
New Mexico ◽  
North America ◽  
Fossil Record ◽  
De Novo ◽  
Upper Triassic ◽  
Late Triassic ◽  
Terrestrial Habitat ◽  
Turtle Shell ◽  
Shell Elements ◽  
Stem Lineage

A new, thin-shelled fossil from the Upper Triassic (Revueltian: Norian) Chinle Group of New Mexico, Chinlechelys tenertesta , is one of the most primitive known unambiguous members of the turtle stem lineage. The thin-shelled nature of the new turtle combined with its likely terrestrial habitat preference hint at taphonomic filters that basal turtles had to overcome before entering the fossil record. Chinlechelys tenertesta possesses neck spines formed by multiple osteoderms, indicating that the earliest known turtles were covered with rows of dermal armour. More importantly, the primitive, vertically oriented dorsal ribs of the new turtle are only poorly associated with the overlying costal bones, indicating that these two structures are independent ossifications in basal turtles. These novel observations lend support to the hypothesis that the turtle shell was originally a complex composite in which dermal armour fused with the endoskeletal ribs and vertebrae of an ancestral lineage instead of forming de novo. The critical shell elements (i.e. costals and neurals) are thus not simple outgrowths of the bone of the endoskeletal elements as has been hypothesized from some embryological observations.

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