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
Abstract
Pycnodonts are an extinct group of bony fishes with crushing dentitions suited to feed on shelled macroinvertebrates. In this paper, we describe a partial skeleton of a large pycnodont collected from the middle Turonian portion of the Boquillas Formation within Big Bend National Park in Brewster County, Texas, USA. The specimen that includes the vomerine and both prearticular tooth plates was determined to taxonomically belong to the genus Macropycnodon, or possibly conspecific with M. streckeri (Hibbard) that is previously known only from a vomerine tooth plate. The complete set of dentition allowed us to support a previous study suggesting that the genus Macropycnodon is a junior synonym of Acrotemnus Agassiz, where the genus is now known from at least four species confined to the Turonian: 1) A. faba (UK); 2) A. streckeri (USA); 3) A. megafrendodon (USA); and 4) an unnamed species of Acrotemnus (Nigeria). The new specimen from Texas is here conservatively referred to as Acrotemnus cf. A. streckeri, and based on the size of the left cleithrum preserved in the specimen, the individual is estimated to be about 1.3 m in total length. Acrotemnus spp. collectively represent a group of large pycnodont fishes that inhabited the seas directly connected to the Tethys Ocean during the Turonian.
- Publication:
-
Cretaceous Research
- Pub Date:
- August 2021
- DOI:
- 10.1016/j.cretres.2021.104797
- Bibcode:
- 2021CrRes.12404797S
- Keywords:
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- Late Cretaceous;
- Paleoecology;
- Pycnodont;
- Tooth plate;
- Western Interior Seaway