Danata Formation

Danata Formation
Stratigraphic range: Early Eocene-Mid Eocene ~56–45  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Location
Coordinates	38°38′N55°48′E / 38.633°N 55.800°E / 38.633; 55.800 [1]
Approximate paleocoordinates	35°06′N51°12′E / 35.1°N 51.2°E / 35.1; 51.2
Country	Turkmenistan
Danata Formation (Turkmenistan)

The Danata Formation (or Danatinskaya, Danatinsk, Russian: Danata Svita) is an earliest Eocene to Middle Eocene sedimentary succession located in Turkmenistan. It is mostly famous for its fish-bearing horizons (Ichthyofauna). ^[1] The formation for example crops out in the Kopet Dag mountain range in the border region of Turkmenistan and Iran. ^[1] It was deposited in a far northeastern arm of the Tethys Sea. ^[2]

Previously, it was thought that the earliest horizons of this formation dated to the latest Paleocene (Thanetian). However, more recent studies have found the formation's sapropel to originate from a global anoxic event caused by the Paleocene-Eocene Thermal Maximum, indicating that it formed just after the Paleocene-Eocene boundary, during the earliest Ypresian. ^[2]

Paleoenvironment

The Danata Formation is famous for its ichthyofauna. The fish are found in a 9 metres (30 ft) thick clay horizon in the middle of the succession, that has been dated as earliest Ypresian, around 56 million years ago. ^{[1] [2]} This includes fossils of the family Turkmenidae. Luvarus necopinatus was first described in this formation. Other fossils of fish include the genera Eospinus, Danatinia, Exellia, Turkmene and Avitoluvarus . The snake species Archaeophis turkmenicus has also been described. ^[3] A similar fauna occurs in the Moler Formation in Denmark. ^[1] The majority of these taxa were named by prominent Russian ichthyologist Pavel Daniltshenko. ^[4]

The fauna is largely dominated by three species: Primisardinella genetrix , Chanos torosus , and Mene triangulum . The formation appears to have been deposited in an open-water environment as the vast majority of genera had a pelagic lifestyle, with only two very rare benthic genera ( Eolamprogrammus and Asanoa ) known. Despite some of the similarities in the taxonomic affiliation of the Danata ichthyofauna with modern-day marine ichthyofauna, only five to six genera represented in the formation ( Chanos , Seriola , Luvarus , Mene , Scomberomorus , and possibly Caesio ) also have modern representatives. Uniquely, a high diversity of luvarid fishes is known from the formation, despite this family being represented by a single, very rare species (the louvar) in the modern day. ^[5]

Paleobiota

The following taxa are known: ^{[4] [5]}

Bony fish

Genus	Species	Notes	Image
Archaeus	A. oblongus	A carangid.
Argestichthys	A. vysotzkyi	A gempylid.
Asanoa	A. kushlukensis	A snake eel.
Asianthus	A. celebratus (= Serranus celebratus)	A perciform of uncertain affinities.
Auxides	A. turkmenicus	A scombrid.
Avitoluvarus	A. dianae	A luvarid.
	A. mariannae
Blochiidae indet.		A blochiid billfish.
? Caesio	? C. breviuscula	A fusilier.
Chanos	C. torosus	A relative of milkfish.
Danatinia	D. casca	A turkmenid lamprimoph.
Eocoelopoma	E. portentosa	A scombrid.
Eolamprogrammus	E. senectus	A viviparous brotula.
Eospinus	E. daniltshenkoi	A bolcabalistid tetraodontiform.
Exellia	E. proxima	An exelliid percomorph.
Georgidens	G. nikolskii	A georgidentid eel.
Goodya	G. danatensis	A halecid aulopiform.
Hemingwaya	H. sarissa	A hemingwayid billfish.
Idrissia	I. turkmenica	A stomiiform of uncertain affinities.
Kushlukia	K. permira	A kushlukiid acanthuriform.
Luvarus	L. necopinatus	A relative of the louvar.
Mene	M. triangulum	A moonfish.
Neocassandra	N. mica	A blackchin.
Opsithrissops	O. osseus	A bonytongue.
Palaeothunnus	P. parvidentatus	A scombrid.
Palimphyes	P. palaeocenicus	A euzaphlegid.
Pauranthus	P. argutulus	A perciform of uncertain affinities.
Platinx	P. cognitus	A late-surviving pachyrhizodontid crossognathiform.
Primisardinella	P. genetrix	A clupeid.
Protorhamphosus	P. parvulus	A macroramphosid.
Pycnodontiformes indet.		A pycnodont.
Scomberomorus	S. avitus	A Spanish mackerel.
Scombrosarda	S. turkmenica	A scombrid.
Seriola	S. paleocenica	A relative of amberjacks.
Siganopygaeus	S. rarus	A relative of rabbitfish.
Trachicaranx	T. tersus (= Uylyaichthys eugeniae)	An apolectid carangiform.
Turkmene	T. finitimus	A turkmenid lamprimoph.
Urosphenopsis	U. sagitta	A urosphenid syngnathiform.

Reptiles

Genus	Species	Notes	Image
" Archaeophis "	"A." turkmenicus	A palaeophiid snake. Assignment to Archaeophis disputed. [6]

References

1. Prokofiev, Artém M. "The Late Paleocene fish fauna of Turkmenistan" (PDF). Archived from the original (PDF) on 15 March 2016. Retrieved 15 November 2013.
2. Bannikov, A. F.; Erebakan, I. G. (2023-10-01). "On the Evolution of Some Groups of Marine Bony Fishes in the Cenozoic of the Tethys and Paratethys". Paleontological Journal. 57 (5): 475–490. Bibcode:2023PalJ...57..475B. doi:10.1134/S0031030123050015. ISSN   1555-6174.
3. Head et al., 2005
4. Bannikov, A. F.; Parin, N. N. (1996). "The List of Marine Fishes From Cenozoic (Upper Paleocene-Middle Miocene) Localities in Southern European Russia and Adjacent Countries". Voprosy Ikhtiologii. 37 (2): 149–161.
5. Банников, Александр Федорович (2009). Ископаемые колючеперые рыбы (Acanthopterygii): систематика, филогения и роль в кайнозойских ихтиокомплексах Тетиса и Паратетиса (Thesis) (in Russian).
6. Gower, David J.; Zaher, Hussam (2022-08-11). The Origin and Early Evolutionary History of Snakes. Cambridge University Press. ISBN   978-1-108-94507-3.

Bibliography

• Head, Jason J.; Holroyd, Patricia A.; Hutchison, J. Howard; Ciochon, Russell L. (2005), "First report of snakes (Serpentes) from the Late Middle Eocene Pondaung Formation, Myanmar", Journal of Vertebrate Paleontology , 25 (1): 246–250, doi:10.1671/0272-4634(2005)025[0246:FROSSF]2.0.CO;2