Faunal composition and paleoenvironment of the Arundel Clay (Potomac Formation; Early Cretaceous), Maryland, USA

Palaeontologia Electronica

Richard L. Cifelli¹  Thomas R. Lipka¹  Joseph A. Frederickson¹ 

[1] Sam Noble Museum

关键词: Joseph A. Frederickson;    Thomas R. Lipka;    Richard L. Cifelli;    Arundel Clay;    Potomac Formation;    Early Cretaceous;    Paleoecology;    dinosaurs;   

DOI  :  10.26879/847

学科分类：地质学

来源: Palaeontologia Electronica

【 摘 要 】

The Arundel Clay facies of the Potomac Group represents one of the few Lower Cretaceous vertebrate-bearing deposits in the Atlantic coastal plain. Vertebrate fossils from this unit have been known for more than 150 years, but thus far formal descriptions have mainly concentrated on its dinosaurs and mammals. Herein, we report on a moderately diverse faunal assemblage (USNM 41614) from Dinosaur Park in Prince Georges County, Maryland. This assemblage is represented by 306 disarticulated macro- and microfossils that largely consist of teeth and scales (89%). This vertebrate fauna includes two species of hybodont sharks, multiple semionotid fishes, one species of lungfish, three species of turtle, three families of neosuchian crocodilians, six species of dinosaurs, and two species of mammals. Combined with other historical collections from this unit, these new additions to the fauna show that the Arundel was a far more robust and diverse ecosystem than previously envisaged, broadly similar in composition to contemporaneous units of western North America. The Arundel assemblage differs, however, from those in many other Lower Cretaceous sites in that it is dominated numerically by Hybodus and goniopholidid crocodylomorphs, which together comprise 58% of catalogued specimens. Similarly, this sample entirely lacks lissamphibians and lepidosaurs. Traditionally, the Arundel has been interpreted as being of fluvial origin, deposited in a freshwater system of stranded channels or oxbows. Based on faunal composition, together with published geological and sedimentological evidence, we propose that at least some of the Arundel facies was deposited in close proximity to the Atlantic Ocean.

【 授权许可】

CC BY