A new pycnodont specimen (Actinopterygii: Pycnodontiformes) from the Upper Cretaceous of Big Bend National Park, Texas, USA, confirming the bony fish genus Macropycnodon as a junior synonym of Acrotemnus

Remains of a large sea turtle, Terlinguachelys fischbecki n. gen. and sp., were recovered from paralic deposits of the Upper Cretaceous (Campanian) Aguja Formation in Big Bend National Park, Texas. T. fischbecki is a primitive protostegid that retains a constricted humerus, well ossified plastron and costals, prominent retroarticular process on the lower jaw, and long slender femora; however, it has some features, such as a prominent tubercle at the base of the scapular acromion process, found elsewhere only in derived leatherback sea turtles. The unique combination of primitive and derived traits in T. fischbecki illustrates further diversity among Cretaceous sea turtles and another case of parallelism common in sea turtle phylogeny.

Download Full-text

Tyrannosauroid dinosaurs from the Aguja Formation (Upper Cretaceous) of Big Bend National Park, Texas

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s1755691013000261 ◽

2012 ◽

Vol 103 (3-4) ◽

pp. 471-485 ◽

Cited By ~ 3

Author(s):

Thomas M. Lehman ◽

Steven L. Wick

Keyword(s):

National Park ◽

Upper Cretaceous ◽

Frontal Bone ◽

Adult Size ◽

Unique Combination ◽

Big Bend National Park ◽

West Texas ◽

Big Bend ◽

Large Predators ◽

Sagittal Crest

ABSTRACTRare remains of tyrannosauroid dinosaurs from the Aguja Formation in West Texas indicate the presence here of a relatively gracile species, comparable in form and adult size to Appalachiosaurus or subadult albertosaurines, Gorgosaurus and Albertosaurus. Histologic analysis of one of the specimens indicates that the Aguja tyrannosaur attained an adult size substantially smaller than adult albertosaurines (700 kg, 6·5 m body length). The frontal bone is narrow with a wide orbital slot and a bipartite joint for the postorbital, features thought to be diagnostic of Albertosaurinae; but there is a tall sagittal crest and reduced parietal wedge separating the frontals on the midline, features thought to be diagnostic of Tyrannosaurinae. The tall sagittal crest may be a synapomorphy of Tyrannosaurinae, and the Aguja tyrannosaur is herein referred to that clade. However, the unique combination of character states exhibited by the frontal prevents confident attribution to any known species. The Aguja tyrannosaur provides further evidence that North American Campanian tyrannosauroids were remarkably diverse for such large predators, and that each species was apparently endemic to a relatively small geographic province.

Download Full-text

Fossil Palms (Arecaceae, Coryphoideae) Associated with Juvenile Herbivorous Dinosaurs in the Upper Cretaceous Aguja Formation, Big Bend National Park, Texas

International Journal of Plant Sciences ◽

10.1086/653688 ◽

2010 ◽

Vol 171 (6) ◽

pp. 679-689 ◽

Cited By ~ 22

Author(s):

Steven R. Manchester ◽

Thomas M. Lehman ◽

Elisabeth A. Wheeler

Keyword(s):

National Park ◽

Upper Cretaceous ◽

Big Bend National Park ◽

Big Bend

Download Full-text

The Boquillas Formation of the Big Bend National Park, Texas, USA, a reference Cenomanian through Santonian (Upper Cretaceous) carbonate succession at the southern end of the Western Interior Seaway

Acta Geologica Polonica ◽

10.1515/agp-2017-0033 ◽

2017 ◽

Vol 67 (4) ◽

pp. 547-565 ◽

Cited By ~ 2

Author(s):

Dee Ann Cooper ◽

Roger W. Cooper ◽

James B. Stevens ◽

M.S. Stevens ◽

William A. Cobban ◽

...

Keyword(s):

Marine Environment ◽

National Park ◽

Upper Cretaceous ◽

Western Interior Seaway ◽

Big Bend National Park ◽

Big Bend ◽

Marine Carbonate ◽

Big Bend Region ◽

C 78

Abstract The upper lower Cenomanian through middle Santonian (Upper Cretaceous) of the Boquillas Formation in the Big Bend Region of Trans-Pecos Texas consists of a marine carbonate succession deposited at the southern end of the Western Interior Seaway. The Boquillas Formation, subdivided into the lower, c. 78 m thick limestone-shale Ernst Member, and the upper, c. 132 m thick limestone/chalk/marl San Vicente Member, was deposited in a shallow shelf open marine environment at the junction between the Western Interior Seaway and the western margins of the Tethys Basin. Biogeographically, the area was closely tied with the southern Western Interior Seaway. The richly fossiliferous upper Turonian, Coniacian and lower Santonian parts of the Boquillas Formation are particularly promising for multistratigraphic studies.

Download Full-text