Triassic Dinosaurs in New Mexico

New Mexico has a relatively sparse Jurassic record of fossil vertebrates, much less than is known from either the Triassic or the Cretaceous strata in the state. The oldest Jurassic vertebrates from New Mexico are the osteichthyans Hulettia americana, Todiltia schoewei and Caturus dartoni from the Middle Jurassic (Callovian) Luciano Mesa Member of the Todilto Formation. The overlying Callovian-Oxfordian? Summerville Formation has yielded fragmentary sauropod dinosaur bones and teeth assigned to Camarasaurus, and theropod footprints identified as Megalosauripus and cf. Therangospodus. Most of New Mexico’s Jurassic vertebrate fossils are from the Upper Jurassic (Kimmeridgian-Tithonian?) Brushy Basin Member of the Morrison Formation and include the turtle Glyptops, the theropod dinosaurs Allosaurus and Saurophaganax, the ornithischian Stegosaurus and (mostly) sauropod dinosaurs identified as Apatosaurus, Brachiosaurus and Diplodocus (= “Seismosaurus”). The sparse record of Jurassic vertebrate fossils in New Mexico is partly due to the extensive eolian and evaporitic facies in parts of the Jurassic section, but mostly to a relative lack of effort to explore the Jurassic strata in New Mexico for vertebrate fossils. 97

Dinosaurs of New Mexico, New Mexico Museum of Natural History and Science Bulletin no, 2000

Cope (1885) published the first scientific report of dinosaur fossils from New Mexico. In the 115 years that followed, discoveries in Triassic, Jurassic and Cretaceous rocks have placed New Mexico in the forefront of dinosaur-collecting grounds (Fig. 1). Analysis of New Mexico's dinosaur fossils has been far reaching, touching upon every aspect of dinosaur paleontology, including biogeography, biostratigraphy, functional morphology, paleoecology, phylogeny, taphonomy and taxonomy. Indeed, this volume brings together ...

Science, 2007

It has generally been thought that the first dinosaurs quickly replaced more archaic Late Triassic faunas, either by outcompeting them or when the more archaic faunas suddenly became extinct. Fossils from the Hayden Quarry, in the Upper Triassic Chinle Formation of New Mexico, and an analysis of other regional Upper Triassic assemblages instead imply that the transition was gradual. Some

Abstract—The Triassic vertebrate paleontological record of New Mexico includes important assemblages of tetrapod fossils from both the Middle Triassic Moenkopi Formation and the Upper Triassic Chinle Group. The Anton Chico Member of the Moenkopi Formation preserves primarily temnospondyl amphibian body fossils, but the record of reptiles comprises both sparse body fossil assemblages and more abundant track assemblages, mostly of chirotheriid reptiles. A bonebed accumulation of temnospondyls assigned to Eocyclotosaurus appetolatus is particularly notable. The Upper Triassic Chinle Group in New Mexico preserves an array of vertebrate faunal assemblages that represent the entirety of Chinle “time,” and includes numerous bonebeds of Revueltian age as well as the best records of Apachean vertebrates in the American West. These include the characteristic assemblages of the Revueltian and Apachean land-vertebrate faunachrons.

Review of the dinosaur record in Mexico until 2006.

2006

Abstract: The holotype of the Late Jurassic sauropod dinosaur Seismosaurus hallorum consists of part of the thoracic and caudal vertebrae, most of the sacrum and pelvis, some ribs and chevrons and an incomplete femur. Reexamination of the holotype indicates that Seismosaurus hallorum differs little from Diplodocus, and none of the morphological differences are significant enough to justify a separate genus. Particularly important to this conclusion has been careful re-examination and further preparation of the ischium of the S ...

For many years the diversity of dinosaurs of Mexico during the Late Cretaceous has been poorly understood. This is due to the limited taxonomical determinations and the abundant undescribed material. This paper presents a new review of the up-to-date osteological record of Late Cretaceous dinosaurs from Mexico, based on published papers, unpublished data and direct observation of the material housed in Mexican paleontological collections and in the field. Some diagnostic dinosaur bones were taxonomically reassigned and others reported in the literature were located in collections. We document new localities with dinosaur remains in Fronteras Sonora, Manuel Benavides and Jiménez Chihuahua, General Cepeda and Saltillo Coahuila. Additionally we report new material relating to tyrannosaurids, ornithomimids, ankylosaurs, ceratopsids and hadrosaurids which extends their geographic and temporal distribution in Mexico. This investigation has revealed a dinosaur faunal assemblage consistent with others studies of North American Late Cretaceous faunas, abundant large bodied dinosaurs and poorly represented small dinosaurs. The lack of oviraptorosaurs, lepoceratopsids and thescelosaurids suggests the need to develop new method in the search for smalldinosaurs in order to gain a more complete picture of dinosaur communities in Mexico and North America during the Late Cretaceous.

2001

Abstract.-Triassic strata in east-central New Mexico are siliciclastic red beds of Middle and Late Triassic age. As much as-500 m thick, the Triassic section is assigned to the Middle Triassic Moenkopi Formation (Anton Chico Member) and overlying Upper Triassic Chinle Group (Santa Rosa, Garita Creek, Trujillo, Bull Canyon and Redonda Formations). The Anton Chico Member of the Moenkopi Formation is as much as 46 m thick and is mostly trough crossbedded micaceous litharenite.