Syntomodus

Syntomodus is an extinct genus of eugeneodont from the Late Permian of Russia. The genus includes a single species, S. abbreviatus, which is known only from a single, poorly preserved set of four teeth. The species may belong to the family Edestidae.^[1][2]

Syntomodus Temporal range: Permian Lopingian PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Chondrichthyes
Order:	†Eugeneodontiformes
Family:	†Edestidae
Genus:	†Syntomodus
Species:	†S. abbreviatus
Binomial name
†Syntomodus abbreviatus Obruchev, 1964
Synonyms
Syntomotus abbreviatus Ginter et al. 2010

Discovery

The holotype specimen of Syntomodus was discovered in a Lopingian-stage deposit in the Yana River Basin of Sakha Republic, Russia. The taxon was named and described by researcher Dmitry Vladimirovich Obruchev.^[1][3] The holotype (and only specimen) is part of the collection of the Palaeontological Institute in Moscow.^[4]

Description

The only known specimen of Syntomodus is incomplete and has been described as poorly preserved.^[1] The teeth are triangular and blade-like, and because of their state of preservation it is unclear if they are angled forwards or backwards. In life they were positioned along the midline, or symphysis, of the jaw.^[1][2]

Classification

When first described by Obruchev, Syntomodus was placed in the family Helicoprionidae, within the order Bradyodonti and the subclass Holocephali.^[4] Syntomodus is now presumed to instead be a member of the family Edestidae, although because the direction its teeth were angled (a characteristic which distinguishes Edestidae and Helicoprionidae) is unclear, this assignment is tentative.^[1][2] In 1981 publication, researcher Rainer Zangerl proposed that Syntomodus is the most basal edestid if it is included in that family.^[2]