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

Late Carboniferous Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * Late (The 77s album), ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudo ...

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 (Urban Zakapa album), ''01'' (Urban Zakapa album), 2011 * ''01011 ...

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

s 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 (also known as orbital revolution) is the curved trajectory of an physical body, object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an satellite, artificia ...

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

gland A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...

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'' Kuhn, 1961; '' Dasyceps'' Huxley 1859; and '' Zatrachys'' 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 transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

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 changes in pressur ...

s in living amphibians. The

choana The choanae (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They ...

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 sep ...

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

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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 (Urban Zakapa album), ''01'' (Urban Zakapa album), 2011 * ''01011 ...

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

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

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 lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

References

{{Taxonbar, from=Q137423 Temnospondyl families Pennsylvanian first appearances Cisuralian extinctions Taxa named by Edward Drinker Cope