Callistomordax

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Callistomordax
Temporal range: Middle Triassic, Ladinian
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Callistomordax kugleri fossil.jpg
Fossil
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Order: Temnospondyli
Suborder: Stereospondyli
Superfamily: Metoposauroidea
Genus: Callistomordax
Schoch, 2008
Type species
Callistomordax kugleri
Schoch, 2008

Callistomordax is an extinct genus of temnospondyl amphibian from the Middle Triassic of Germany. The type and only species, Callistomordax kugleri, was named in 2008. It is known from several well-preserved skeletons found in the Erfurt Formation, part of the Lower Keuper, which dates back to the late Ladinian stage. [1]

Contents

History of study and provenance

The first specimen of Callistomordax kugleri, which is currently reposited at the Staatliches Museum für Naturkunde (SMNS) in Stuttgart, Germany, was collected from the Middle Triassic (Upper Ladinian-aged) Erfurt Formation of Baden-Württemberg by Werner Kugler, for whom the species is named. Various authors speculated on the taxonomic affinities of the specimen, but it was not formally resolved until 2008. [1] The specimen was subsequently donated to the SMNS and additional excavation at the original locality in 2000 led to the discovery of two nearly complete skeletons by private collectors Hans Michael Salomon and Traugott Haubold.

Anatomy

Callistomordax was distinguished from other temnospondyls by characters such as a single co-ossified frontal (normally paired in tetrapods), a pterygoid with both a broad and flat quadrate ramus and a slender and narrow palatine ramus, and lateral compression of the palatal and symphyseal fangs. [1] It shares a number of metoposaurid synapomorphies such as deeply sloping postparietals and tabulars but also retains more primitive features found in earlier diverging temnospondyls and a number of probable homoplasies.

Ecology

As with many Triassic temnospondyls, Callistomordax is considered to have been an aquatic freshwater tetrapod, evidenced by both its anatomy (e.g., lateral line system) and its depositional environment. The Lower Keuper Basin where Callistomordax was found was subjected to repeated transgression-regression cycles, resulting in mixed deposits of freshwater and marine taxa. Callistomordax is relatively rare and consists only of isolated elements in bonebeds with higher abundances of marine taxa, and the most complete specimens are found with various invertebrates and fish that suggest a relatively low salinity environment.

Phylogeny

Below is a cladogram from Schoch (2008):

Stereospondyli

Rhinesuchidae

Lydekkerina

Rhytidosteidae

Brachyopoidea

Siderops

Batrachosuchus

Laidleria

Plagiosauroidea

Gerrothorax

Plagiosaurus

Capitosauroidea

Trematosauria

Aphaneramma

Trematolestes

Lyrocephaliscus

Rileymillerus

Almasaurus

Callistomordax

Metoposauridae

Callistomordax is significant in filling a gap in the fossil record that inhibited firm conclusions regarding the origins of the Metoposauridae, which had previously been variably suggested to be placed in the Permian Dvinosauria or within the Triassic Trematosauria. As seen in the above phylogeny, Callistomordax is the sister taxon to the Metoposauridae and places the Metoposauroidea (Metoposauridae + Callistomordax) within Trematosauria.

Related Research Articles

Temnospondyli Ancestors of modern amphibians adapted to life on land

Temnospondyli is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carboniferous, Permian, and Triassic periods. A few species continued into the Cretaceous. Fossils have been found on every continent. During about 210 million years of evolutionary history, they adapted to a wide range of habitats, including fresh water, terrestrial, and even coastal marine environments. Their life history is well understood, with fossils known from the larval stage, metamorphosis, and maturity. Most temnospondyls were semiaquatic, although some were almost fully terrestrial, returning to the water only to breed. These temnospondyls were some of the first vertebrates fully adapted to life on land. Although temnospondyls are considered amphibians, many had characteristics, such as scales, claws, and armour-like bony plates, that distinguish them from modern amphibians.

<i>Gerrothorax</i> Extinct genus of amphibians

Gerrothorax is an extinct genus of temnospondyl amphibian from the Triassic period of Greenland, Germany, Sweden, and possibly Thailand. It is known from a single species, G. pulcherrimus, although several other species such as G. pustuloglomeratus have been named in the past.

<i>Metoposaurus</i> Extinct genus of amphibians

Metoposaurus meaning "front lizard" is an extinct genus of stereospondyl temnospondyl amphibian, known from the Late Triassic of Germany, Italy, Poland, and Portugal. This mostly aquatic animal possessed small, weak limbs, sharp teeth, and a large, flat head. This highly flattened creature mainly fed on fish, which it captured with its wide jaws lined with needle-like teeth. Metoposaurus was up to 3 m long and weighed about 450 kg. Many Metoposaurus mass graves have been found, probably from creatures that grouped together in drying pools during drought.

Stereospondyli Extinct suborder of amphibians

The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecological niche to modern crocodilians prior to the diversification of pseudosuchian archosaurs.

<i>Batrachotomus</i>

Batrachotomus is a genus of prehistoric archosaur. Fossils of this animal have been found in southern Germany and dated from the Ladinian stage of the Middle Triassic period, around 242 to 237 million years ago. Batrachotomus was described by palaeontologist David J. Gower 22 years after its discovery.

<i>Trematolestes</i> Extinct genus of amphibians

Trematolestes is an extinct genus of temnospondyl amphibian from the Lower Keuper of southern Germany. It was first named by Rainer R. Schoch in 2006 and the type species is Trematolestes hagdorni. It is the first trematosaurid represented by a nearly complete skeleton.

Plagiosauridae Extinct family of amphibians

Plagiosauridae is a clade of temnospondyl amphibians of the Middle to Late Triassic. Deposits of the group are most commonly found in non-marine aquatic depositional environments from central Europe and Greenland, but other remains have been found in Russia, Scandinavia, and possibly Thailand.

Almasaurus is an extinct genus of trematosaurian temnospondyl within the family Latiscopidae. It is known from several skulls and some postcranial material found from the Argana Formation in Morocco, which dates back to the Late Triassic.

Rileymillerus is an extinct genus of temnospondyl amphibian from the Late Triassic Post Quarry in the Dockum Group of Texas that was described by John Bolt and Sankar Chatterjee in 2000. The holotype, a nearly complete skull with articulated jaws, is housed at the Museum of Texas Tech University. The genus is named for Riley Miller, who allowed Chatterjee to work on the Post Quarry, and the species is named for the paleontologist John Cosgriff.

<i>Plagiosuchus</i> Extinct genus of amphibians

Plagiosuchus is an extinct genus of plagiosaurid temnospondyl. It is known from several collections from the Middle Triassic of Germany.

Tangasauridae

Tangasauridae is a family of eosuchian diapsids. Specimens have been found that are of Late Permian to Early Triassic in age from the Sakamena Group of western Madagascar. They lived alongside other taxa present from the Sakamena Group, including temnospondyls, rhynchosaurs, and gomphodont eucynodonts. Fossils have been found of numerous specimens of common members of this family such as Hovasaurus and Thadeosaurus in different stages of ontogenic development. Recent material from the Middle Sakamena Formation of the Morondava Basin of Madagascar that dates back to the early Triassic period suggests that the Tangasauridae were relatively unaffected by the Permian-Triassic extinction event.

<i>Anaschisma</i> Extinct genus of amphibians

Anaschisma is an extinct genus of large temnospondyl amphibians. These animals were part of the family called Metoposauridae, which filled the crocodile-like predatory niches in the late Triassic. It may have reached up to 3 m (10 ft) in length, with a 65-cm-long skull. It was an ambush hunter, snapping up anything small enough to fit in its huge jaws. It was very common during the Late Triassic in what is now the American Southwest.

Capitosauria Extinct clade of amphibians

Capitosauria is an extinct group of large temnospondyl amphibians with simplified stereospondyl vertebrae. Mainly living as piscivores in lakes and rivers, the Capitosauria and its sister taxon Trematosauria were the only major labyrinthodonts that existed during the Mesozoic in ecological niches broadly similar to those of modern crocodiles, and some grew to very large sizes. At 6 meter in length, the Mid-Triassic Mastodonsaurus giganteus is not only thought to have been the largest capitosaur, but possibly also the largest amphibian to have lived. The latest known remains are from the Rhaetian of Germany and are referred to Cyclotosaurus.

Colognathus is a genus of extinct reptile from Late Triassic rocks of the southwestern United States. It was described in 1928 from a jaw fragment by Case, who interpreted the new taxon as a fish. The type species is C. obscurus.

<i>Bystrowiella</i> Extinct genus of amphibians

Bystrowiella is an extinct genus of bystrowianid reptiliomorph from upper Middle Triassic deposits of Kupferzell and Vellberg, northern Baden-Württemberg, Germany. It was first named by Florian Witzmann, Rainer R. Schoch and Michael W. Maisch in 2008, from a complete osteoderm fused with tip of neural spine, partial osteoderms and vertebrae. The type species is Bystrowiella schumanni. The genus is named in honour of Dr. Alexey Bystrow, a Russian paleontologist and the species in honour of Schumann family. Bystrowiellas closest relative was Synesuchus.

Erfurt Formation

The Erfurt Formation, also known as the Lower Keuper, is a stratigraphic formation of the Keuper group and the Germanic Trias supergroup. It was deposited during the Ladinian stage of the Triassic period. It lies above the Upper Muschelkalk and below the Middle Keuper.

Jaxtasuchus is an extinct genus of armored doswelliid archosauriform reptile known from the Middle Triassic of the Erfurt Formation in Germany. The type species, Jaxtasuchus salomoni, was named in 2013 on the basis of several incomplete skeletons and other isolated remains. Like other doswelliids, members of the genus were heavily armored, with four longitudinal rows of bony plates called osteoderms covering the body. Jaxtasuchus is the first doswelliid known from Europe and is most closely related to Doswellia from the Late Triassic of the eastern United States. However, it was not as specialized as Doswellia, retaining several generalized archosauriform characteristics and having less armor. Jaxtasuchus fossils have been found in aquatic mudstones alongside fossils of temnospondyl amphibians, crustaceans, and mollusks, suggesting that Jaxtasuchus was semiaquatic like modern crocodilians.

Latiscopus disjunctus is a small Late Triassic temnospondyl collected in 1940 by a Works Projects Administration crew working near Otis Chalk, Texas that was described by John Wilson in 1948.

Fraxinisaura is an extinct genus of basal lepidosauromorph reptile known from the Middle Triassic of Germany. The only known species is Fraxinisaura rozynekae. It possessed an elongated snout, unique features of the teeth, and an ilium which was intermediate in orientation between sphenodontians and squamates. Based on characteristics of the maxilla, it is considered a close relative of Marmoretta from the Middle Jurassic of the United Kingdom, resolving a ghost lineage between that genus and other Triassic basal lepidosauromorphs.

<i>Polymorphodon</i>

Polymorphodon is an extinct genus of archosauriform reptile from the Middle Triassic of Germany. The only known species is Polymorphodon adorfi, discovered in Lower Keuper deposits at a quarry in Eschenau, Germany. Polymorphodon is notable for its heterodont dentition, with long and conical premaxillary teeth followed by thin maxillary teeth with large serrations. Maxillary teeth near the back of the mouth are short and leaf-shaped, similar to some living and extinct reptiles with a herbivorous or omnivorous diet. This may suggest that Polymorphodon had some reliance on plants in its diet, a rarity among basal archosauriforms, most of which are carnivores.

References

  1. 1 2 3 Schoch, R. R. (2008). "A new stereospondyl from the German Middle Triassic, and the origin of the Metoposauridae". Zoological Journal of the Linnean Society. 152: 79–113. doi: 10.1111/j.1096-3642.2007.00363.x .