Trematosauridae is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of large marine

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 with several included

genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...

Appearance and lifestyle

Trematosaurids are one of the most derived families of the

Trematosauroidea Trematosauroidea are an important group of Triassic temnospondyl amphibians. They flourished briefly during the Early Triassic, occurring worldwide before declining at the start of the Middle Triassic, although the group continued until the Late ...

superfamily in that they are the only family that have fully marine lifestyles. Long, slender snouts that are characteristic of the trematosaurids, with some members having

rostra The Rostra () was a large platform built in the city of Rome that stood during the republican and imperial periods. Speakers would stand on the rostra and face the north side of the Comitium towards the senate house and deliver orations to t ...

resembling those of modern-day gavials. Traditionally, two subfamilies within Trematosauridae can be identified, the relatively short-nosed

Trematosaurinae Trematosaurinae is a subfamily of temnospondyl amphibians within the family Trematosauridae. Like all trematosaurids, they were marine piscivores, resembling crocodiles in their general build. Unlike the long, almost gharial-like snouts of the Lo ...

and the long-nosed

Lonchorhynchinae Lonchorhynchinae is a subfamily of temnospondyl amphibians within the family Trematosauridae. Classification Below is a cladogram from Steyer (2002) showing the phylogenetic In biology, phylogenetics () is the study of the evolutionary h ...

. A third subfamily, Tertreminae, was named in

2000 2000 was designated as the International Year for the Culture of Peace and the World Mathematics, Mathematical Year. Popular culture holds the year 2000 as the first year of the 21st century and the 3rd millennium, because of a tende ...

and includes broad-snouted forms like ''

Tirraturhinus ''Tirraturhinus'' is an extinct genus of trematosaurian temnospondyl within the family Trematosauridae. The type species is ''T. smisseni''. See also * Prehistoric amphibian * List of prehistoric amphibians This list of prehistoric amphibians i ...

''.

Fossil record

Trematosaurids first appeared during the

Induan The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.9 Ma and 249.9 Ma (million years ago). The Induan is so ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

(

Wordie Creek Formation The Wordie Creek Formation is an uppermost Permian and Lower Triassic geologic formation in Greenland, outcrops of which are located in Northeast Greenland National Park (until 2008 Tunu County, Danish: Østgrønland, English: East Greenland). ...

, Greenland) of the

Early Triassic The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 251.9 Ma and Ma (million years ago). Rocks from this epoch are collectively known as the Lower Triassic Series, which ...

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided b ...

. The family existed until around the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...

age of the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...

epoch, although by then they were very rare. By the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...

they had become widespread throughout

Laurasia Laurasia () was the more northern of two large landmasses that formed part of the Pangaea supercontinent from around ( Mya), the other being Gondwana. It separated from Gondwana (beginning in the late Triassic period) during the breakup of Pa ...

and

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

with fossils being found in Europe, Asia, Madagascar, and Australia. A possible trematosaurid has been found in the

Toutunhe Formation The Toutunhe Formation is a Late Jurassic geological formation in China, specifically dating to the Oxfordian and Kimmeridgian stages. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the format ...

in the

Junggar Basin The Junggar Basin (), also known as the Dzungarian Basin or Zungarian Basin, is one of the largest sedimentary basins in Northwest China. It is located in Dzungaria in northern Xinjiang, and enclosed by the Tarbagatai Mountains of Kazakhstan in t ...

. If this analysis is accurate, it renders Trematosauridae one of the longest lived lineages of the

Temnospondyli Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—often considered primitive amphibians—that flourished ...

, having lasted as recently as the late Jurassic. In 2006, a new Middle Triassic genus ''

Trematolestes ''Trematolestes'' is an extinct genus of temnospondyl amphibian from the Lower Keuper (Ladinian, Middle Triassic) of southern Germany. It was first named by Rainer R. Schoch in 2006 and the type species is ''Trematolestes hagdorni''. It is the fi ...

'' from southern Germany has been reported. It was the sister taxon of the subfamily

and its closest relative was ''

Tertremoides ''Tertremoides'' is an extinct genus of trematosaurian temnospondyl within the family Trematosauridae from Madagascar. It was first named by Lehman, J-P. in 1966 as '' Trematosaurus madagascariensis'' but renamed to ''Tertremoides ambilobensis'' ...

''.

Phylogeny

Below is a

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

from Steyer (2002) showing the

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

relationships of trematosaurids: A cladogram after Novikov (2018) with only Early Triassic Eastern Europe taxa included:

References

External links

Trematosauridae
at

Palaeos Palaeos.com is a web site on biology, paleontology, phylogeny and geology and which covers the history of Earth. The site is well respected and has been used as a reference by professional paleontologists such as Michael J. Benton, the professor of ...

Trematosauridae Temnospondyl families Early Triassic first appearances Carnian extinctions {{Temnospondyli-stub