''Laytonia'' is an extinct genus of prehistoric

halosaur Halosaurs are eel-shaped fishes found only at great ocean depths. As the family Halosauridae, halosaurs are one of two families within the order Notacanthiformes; the other being the deep-sea spiny eels, Notacanthidae. Halosaurs are thought to ha ...

that lived in deep water off the North American Pacific Coast from the Zemorrian Epoch (comprising either the latest

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

or lower Miocene) until during the

Upper Miocene The Late Miocene (also known as Upper Miocene) is a sub-epoch of the Miocene Epoch made up of two stages. The Tortonian and Messinian stages comprise the Late Miocene sub-epoch, which lasted from 11.63 Ma (million years ago) to 5.333 Ma. The ev ...

subepoch, when

tectonic uplift Tectonic uplift is the geologic uplift of Earth's surface that is attributed to plate tectonics. While isostatic response is important, an increase in the mean elevation of a region can only occur in response to tectonic processes of crustal th ...

effectively destroyed the genus' habitat by making the deep water too shallow.David, Lore Rose. January 10, 1943. Miocene Fishes of Southern California The Society There are two species recognized, the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, ''L. californica'', which is known from at least 2 whole fossils, and fossil scales from Upper Miocene strata of Southern California, and ''L. zemorrensis'', known from fossil scales in Zemorrian strata (either Oligocene or Lower Miocene) from Oregon and California. According to the fossils of ''L. californica'', the living animals were very slender, and had a long, fringe-like dorsal fin running almost the entire length of the body, from the head to the tip of the tail. The dorsal fin forms two crests, a first, low crest on top of the back of the head, and a second, large crest near the upper back, above the pectoral fins. The name comes from discoverer of the fossil, Melvin E. Layton.

References

Halosauridae Miocene fish of North America {{notacanthiformes-stub

See also

References