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[dinosaur] Hadrosaur specimen taphonomic history from Upper Cretaceous, Coahuila, Mexico





Ben Creisler
bcreisler@gmail.com

A new paper:

Claudia Inés Serrano-Brañas and Belinda Espinosa-Chávez (2017)
Taphonomic history of a ‘duck-bill’ dinosaur (Dinosauria: Ornithopoda) from the Cerro del Pueblo Formation (Upper Cretaceous, Campanian) Coahuila, Mexico: Preservational and paleoecological implications.
Cretaceous Research (advance online publication)
doi: http://dx.doi.org/10.1016/j.cretres.2017.02.022
http://www.sciencedirect.com/science/article/pii/S0195667116303755

Highlights

This research corresponds to the first formal taphonomic study performed on the dinosaur assemblages of the Cerro del Pueblo Formation.
Taphonomic analysis revealed that the hadrosaur specimen was transported as a “bloated carcass”.
Fine-grained sediments and plant remains protected the hadrosaur carcass from abrasion.
The carcass experienced a shortly subaerial exposure and the burial probably occurred during the first year after dead.
The tooth marks present on some of the bones could be mostly referred to crocodylians.
Trampling activities were exerted by other animals within the hadrosaur's death assemblage.

Abstract

The Cerro del Pueblo Formation in the state of Coahuila, Mexico is becoming recognized worldwide due to its abundant and diverse fossil material. While most previous paleontological work from this rock unit has been directed towards taxonomic investigation, this study is directed towards the taphonomy of a “duck-billed” dinosaur (Ornithischia: Hadrosauridae). The hadrosaur skeleton is represented by several skull bones, vertebrae and ribs, a scapula, pubis, and various appendicular elements. The following taphonomic parameters were considered: (1) bone frequency; (2) hydraulic equivalence; (3) degree of bone articulation; (4) abrasion; (5) weathering; (6) breakage; (7) tooth marks; and (8) trampling activities. The low degree of weathering and abrasion suggests that the specimen experienced a short time of subaerial exposure and underwent a short transportation distance before deposition. Burial occurred within a perimarine lagoonal environment. Furthermore, the lack of hydraulic equivalence with the rock matrix, a high degree of disarticulation and a chaotic distribution of the bones in the fossiliferous bed, suggest that it was transported as a "bloated carcass". The finding of distinct types of tooth marks evidence some sort of predator/scavenging activities on the specimen. Finally, an almost vertical orientation of various bones and the presence of spiral fractures may indicate that these elements were trampled by other animals.