Acheloma (Redirected from Trematops)

Acheloma
Temporal range: Early Permian, 279.5–272.5 Ma
Acheloma-Field Museum.jpg
Skeletal mount of A. cumminsi, Field Museum of Natural History
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Temnospondyli
Family: Trematopidae
Genus: Acheloma
Cope, 1882
Species
  • A. cumminsi Cope, 1882
  • A. dunni Polley & Reisz, 2011
Synonyms

Trematops milleri Williston, 1909 Trematops thomasi Mehl, 1926 Trematops willistoni Olson, 1941 Trematops stonei Williston, 1970

Restoration of A. cumminsi

Acheloma (also known as Trematops milleri) is an extinct genus of temnospondyl that lived during the Early Permian. The type species is A. cumminsi.

History of study

Acheloma was named by Edward Drinker Cope in 1882 based on a partial skull with associated postcranial elements from the Arroyo Formation of Texas; the specimen is currently reposited at the American Museum of Natural History in New York. Subsequent discoveries of large trematopids from the Arroyo Formation were named as different species of Trematops (T. milleri, T. willistoni), but these have since been synonymized with Acheloma cumminsi. Trematops stonei from the Washington Formation of Ohio and Trematops thomasi from Oklahoma have also been synonymized with A. cumminsi. A second species of Acheloma was described by Polley & Reisz (2011) from the Richards Spur locality in Oklahoma.

Anatomy

Schoch & Milner (2014) provide nine characters in their diagnosis of Acheloma: (1) toothed crest on the vomer extending medial to the internal naris; (2) constricted otic notch with nearly horizontal ventral margin; (3) preorbital region twice as long as the skull table; (4) naris twice as long as the orbit; (5) posterior skull table wide and posterolaterally expanded; (6) skull margin widens at level of and posterior to orbit; (7) palatine and ectopterygoid with tall fangs; (8) large intervomerine fenestra; and (9) choana elongate and curved with a Y-shaped contour. Acheloma cumminsi and A. dunni are distinguished by the purported absence of lateral exposures of the palatine (LEP) and the ectopterygoid (LEE) in A. cumminsi, but these exposures were subsequently identified following re-examination of the holotype of this taxon.

Ecology

Various analyses have confirmed hypotheses that Acheloma was a terrestrial temnospondyl.

Phylogeny

The following cladogram shows the phylogenetic position of Acheloma, from Polley & Reisz, 2011.

Dissorophoidea 

Sclerocephalus haeuseri

Micromelerpeton credneri

Micropholis stowi

Eoscopus lockardi

 Olsoniformes 

Cacops morrisi

 Trematopidae 

Phonerpeton pricei

 Acheloma 

Acheloma cumminsi

Acheloma dunni

Actiobates peabodyi

Ecolsonia cutlerensis

Anconastes vesperus

Tambachia trogallas




This page was last updated at 2023-05-03 11:42 UTC. Update now. View original page.

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