Syntomodus

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

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]}

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]

References

1. Ginter, Michał; Hampe, Oliver; Duffin, Christopher J. (2010). Handbook of paleoichthyology: teeth. München: F. Pfeil. p. 132. ISBN   978-3-89937-116-1.
2. Zangerl, Rainer (1981). Chondrichthyes 1: Paleozoic Elasmobranchii (Handbook of Paleoichthyology). Friedrich Pfell (published January 1, 1981). pp. 2–3, 74–94. ISBN   978-3899370454.
3. Obroucheva, Natalie V. (2014). "Dmitry Vladimirovich Obruchev: Life and destiny (1900–1970)" . Paleontological Journal. 48 (9): 950–963. doi:10.1134/S0031030114090093. ISSN   0031-0301.
4. Obruchev, Dmitry (1967). Fundamentals of paleontology. A manual for paleontologists and geologists of the USSR. Vol. 11. Jerusalem: Israel Program for Scientific Translations. pp. 353–419.