Zatracheidae (sometimes mistakenly spelled Zatrachydidae or Zatrachysdidae) is a family of

Late Carboniferous Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

and

Early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

amphibians known from North America and Europe. Zatracheidids are distinguished by lateral (sideways) bony protuberances of the

quadratojugal The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

bone of the skull, and a large opening in the snout called the internarial fontanelle (sometimes the internarial fenestra) that is bordered by enlarged premaxillae. The skull is flattened, with small

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

or eye sockets set far back. The opening in the snout may have housed a

gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...

for producing a sticky substance so that prey would adhere to the tongue. If so, this indicates that these animals spent a large part of their time on land.

History of study

There are three genera of zatracheidids: ''

Acanthostomatops ''Acanthostomatops'' is an extinct genus of zatracheidid temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of sma ...

'' Kuhn, 1961; ''

Dasyceps ''Dasyceps'' is an extinct genus of zatracheidid temnospondyl from the early Permian of England. History of study ''Dasyceps'' was originally named in 1850 for the type species, ''D. bucklandi'', which honors English paleontologist William Bu ...

'' Huxley 1859; and ''

Zatrachys ''Zatrachys'' is an extinct genus of large and flat-headed zatracheidid temnospondyl from the early Permian of North America. History of study ''Zatrachys'' was named by American paleontologist Edward Drinker Cope in 1878 for the type species ...

'' Cope, 1878. Only ''Dascyeps'' is represented by a species in addition to the type species. The name Zatracheidae was first coined by Cope (1882). Numerous variations on this, such as 'Zatrachydae' and 'Zatrachydidae' have been used in the literature, as have permutations derived from ''Acanthostomatops'' such as 'Acanthostomidae.'

Anatomy

Zatracheidids are recognized by their wide and flat skulls with a greatly enlarged preorbital region that is distinguished by the large internarial fontanelle, with corresponding large premaxillae. A correspondingly large intervomerine fontanelle is found on the palate. The quadratojugal is expanded, and in ''Acanthostomatops'' and ''Zatrachys'', bears discrete spiky projections. The quadratojugal also obscures the quadrate in dorsal profile. ''Dasyceps'' and ''Zatrachys'' are only confidently known from cranial material.

Development

Zatracheidids are one of several temnospondyl groups that are speculated to have undergone

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

from young to adult. Both ''Zatrachys'' and ''Acanthostomatops'' are known from ontogenetic series, but that of ''Acanthostomatops'' is more complete and is the only one that would definitively capture metamorphosis. Spikes developed during metamorphosis, and as zatrachydids continued growing as adults, the pits and grooves on their skulls grew more extensive and the otic notch at the back of the skull grew wider. These notches likely supported membranes called tympana, which serve as

ear drum In the anatomy of humans and various other tetrapods, the eardrum, also called the tympanic membrane or myringa, is a thin, cone-shaped membrane that separates the external ear from the middle ear. Its function is to transmit sound from the air ...

s in living amphibians. The

choana The choanae (singular choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the throat in tetrapods, including humans and other mammals (as well as crocodilia ...

e also grew larger during metamorphosis, and are distinguished by their irregular shape, which differs from the more circular shape seen in other temnospondyls. Zatrachydids also possess a hole in the center of their

palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...

s called the inter-vomerine fontanelle, which grows larger during metamorphosis. This hole is seen in living salamanders and frogs and is associated with an organ called the intermaxillary gland, which produces secretions that make the tongue sticky. It may also have been present in zatrachydids.

Gallery

Zatrachys1DB.jpg, '' Zatrachys serratus'', of the

late Carboniferous Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

and

early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

of North America Dasyceps bucklandi.jpg, '' Dasyceps bucklandi'', of the early Permian of

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

Acanthostomatops vorax.jpg, '' Acanthostomatops vorax'', of the early Permian of

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

References

{{Taxonbar, from=Q137423 Carboniferous temnospondyls Permian temnospondyls Rhachitomes Pennsylvanian first appearances Cisuralian extinctions Prehistoric amphibian genera Taxa named by Samuel Wendell Williston