Euromycter

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Euromycter
Temporal range: Cisuralian (late Artinskian, ~ 285  Ma
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Euromycter rutenus.jpg
Skull cast
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade:† Caseasauria
Family:† Caseidae
Genus:† Euromycter
Reisz et al., 2011
Species
  • † E. rutenus(Sigogneau-Russell & Russell, 1974) (type)
Synonyms
  • Casea rutenaSigogneau-Russell & Russell, 1974

Euromycter is an extinct genus of caseid synapsids that lived in what is now southern France during the Early Permian (late Artinskian) about 285 million years ago. The holotype and only known specimen of Euromycter (MNHN.F.MCL-2) includes the complete skull with lower jaws and hyoid apparatus, six cervical vertebrae with proatlas, anterior part of interclavicle, partial right clavicle, right posterior coracoid, distal head of right humerus, left and right radius, left and right ulna, and complete left manus. It was collected by D. Sigogneau-Russell and D. Russell in 1970 at the top of the M1 Member, Grès Rouge Group, near the village of Valady (département of Aveyron), Rodez Basin. It was first assigned to the species "Casea" rutena by Sigogneau-Russell and Russell in 1974. More recently, it was reassigned to its own genus, Euromycter, by Robert R. Reisz, Hillary C. Maddin, Jörg Fröbisch and Jocelyn Falconnet in 2011. [1] The preserved part of the skeleton suggests a size between 1,70 m (5,5 ft) and 1,80 m (5,9 ft) in length for this individual. [2]

Contents

Etymology

The generic name refers to the location of the taxon in Europe, and “mycter” = nose, refers to the enlarged external naris that characterizes the caseids. [1] The species epithet refers to ruteni (Les Rutènes in French) the Latin name of the Gallic tribe that lived in the Rodez area. [3]

Description

Skull of Euromycter rutenus in ventral view allowing to see the numerous small teeth adorning the bones of the palate (the parasphenoid, triangular in shape in the center, and the very elongated pterygoids on each side). The hyoid apparatus is not present here because it was removed during the preparation of the palate. Euromycter rutenus 6778 retouched.jpg
Skull of Euromycter rutenus in ventral view allowing to see the numerous small teeth adorning the bones of the palate (the parasphenoid, triangular in shape in the center, and the very elongated pterygoids on each side). The hyoid apparatus is not present here because it was removed during the preparation of the palate.

The skull is well-preserved but has suffered of a slight flattening as a result of a tectonic thrust exerted toward the right side and the front. As in other caseid, the skull is small compared to the skeleton (here mainly the forelimbs), and shows very large external nares, a short facial region, and a dorsal surface of the skull dotted of numerous small depressions. In addition, they are many palatal teeth, and the teeth of the upper jaws are numerous (four premaxillary and eleven maxillary teeth) and spatulated with crowns having 5 to 8 cusps. [3] The front teeth, fairly long and slightly recurved, were probably suited to aid in gathering vegetation into the mouth, whereas it is presumed that palatal teeth had to work in conjunction with a tough and massive muscular tongue as indicated by the presence of a very well-developed hyoid apparatus. [4] [5]

Characteristically, Euromycter shows an unusually broad skull, large temporal fenestra, and lack of expansion of the axial neural spine. It can be distinguished from other caseids by the presence of a supernumerary blade-like intranarial bone located posteromedially to the septomaxilla, proportional differences in forelimb and manus, presence of an accessory proximal articulation between metacarpals 3 and 4, medial recurvature of metacarpal, and its manual phalangeal formula of 2-3-4-4-3. [3] [1]

Stratigraphic range

Size and body proportions of Euromycter rutenus Euromycter size chart.jpg
Size and body proportions of Euromycter rutenus

The holotype of Euromycter comes from the top of the red pelitic beds of the M1 Member, in the basal part of the Grès Rouge (“Red Sandstone”) Group, a sedimentary sequence subdivided into five hectometric members (M1 to M5) localized in the western Rodez basin. The deposits are interpreted as a playa-lake environment (or Sabkha) under a semi-arid, hot climate. [1] The age of the Grès Rouge Group is uncertain but it is regarded as contemporaneous to the Saxonian Group of the neighbouring Lodève basin, where radiometric and magnetostratigraphic data suggested previously an age between the late Sakmarian (middle of the Early Permian) and the early Lopingian (early Late Permian). [6] [1] However, new chronostratigraphic and magnetostratigraphic data for the Saxonian Group indicate an age between the Artinskian (for the Rabejac Formation and the Octon Member of the Salagou Formation) and the late Roadian-Wordian and possibly early Capitanian (for La Lieude Formation). [7] [8] A more precise stratigraphic correlation of the Permian Rodez basin with that of Lodève was proposed in 2022 by Werneburg and colleagues. In the Rodez basin, the FII Formation of the Salabru Group, underlying the Grès Rouge Group, yielded palynomorphs, conchostracans, and a tetrapod footprints assemblage equivalent to that of the Viala Formation of the Lodève basin. [9] The lower part of the Viala Formation yielded a radiometric age of 290.96 ± 0.19 Ma corresponding to the late Sakmarian. [8] It has also been determined that the M1 and M2 megasequences of the Rodez basin are equivalent to the Rabéjac Formation of the Lodève basin (and also of the Combret Member of the Saint-Pierre Formation of the Saint-Affrique basin in southern Aveyron). [9] Above the Rabéjac Formation, the lower two-thirds of the Octon Member of the Salagou Formation yielded four tuff horizons radiometrically dated. The oldest tuff horizon provided an age of 284.40 ± 0.07 Ma corresponding to the latest Artinskian. [8] Based on this dating, the Rabéjac Formation and the correlative M1 and M2 megasequences of the Grès Rouge Group can be dated to the late Artinskian. [9] A conclusion consistent with the magnetostratigraphy which suggests that the entire Grès Rouge Group (members M1 to M5) would have an age between the late Artinskian and the early Wordian. [9]

Discovery

Euromycter rutenus : skull in lateroventral view Euromycter rutenus 73643 retouched.jpg
Euromycter rutenus : skull in lateroventral view

During a prospecting survey carried out in the Permian red sandstones outcropping in badlands on the western flank of the Cayla Hill (commune of Valady, northwest of Rodez), the paleontologists Denise Sigogneau-Russell and Donald Eugene Russell discovered in the summer of 1970 the skeletons of two herbivorous reptiles. An eroded vertebra picked up on the western slope of the hill led the scientists to explore the surrounding canyons where they discovered a large articulated skeleton still in place in the sediments but damaged by erosion. The skull, neck, most of the limbs, and the tail had been washed away and destroyed. On the southeastern flank of the same hill, the same team discovered a bone fragment from a different animal. The systematic exploration of surrounding slopes permitted the discovery of bones still in place in the rock belonging to a smaller animal than the first. The whole back of the skeleton had already destroyed by erosion. The right forearm was exposed at the surface of the rock, then was found the skull, several articulated cervical vertebrae, the left forearm articulated with the complete left manus, a piece of the right humerus and parts of the right shoulder. Both specimens were identified as caseids pelycosaurs. The smaller specimen found at about two kilometers horizontally from the first skeleton, but 120 meters lower stratigraphically, was described in 1974 and assigned to a new species of the genus Casea , Casea rutena. This animal was celebrated as the first caseid found in Western Europe, making of this species a geographical link with other specimens of the family that were previously known only in the south central United States (Texas and Oklahoma) and in the northern European Russia. [3]

In 2008, a phylogenetic analysis of Caseidae demonstrates the paraphyly of the genus Casea, the French species representing a distinct unnamed genus. [10] Three years later, the species Casea rutena was removed of the genus Casea and assigned to a new genus, Euromycter, in the new combination Euromycter rutenus. In the same article the authors described the larger and stratigraphycally younger skeleton from the Cayla Hill, and assigned it to a new genus named Ruthenosaurus . [1]

Classification

In the first phylogenetic analysis of the caseids published in 2008, Euromycter, then still designated as “Casea” rutena, was recovered as the sister taxon to a derive clade containing Ennatosaurus tecton , Cotylorhynchus romeri and Angelosaurus dolani .

Below the first phylogenetic analysis of Caseidae published by Maddin et al. in 2008. [10]

  Caseasauria

A phylogenetic analysis made by Benson shows a similar position for Euromycter (again regarded as “Casea” rutena).

Below the phylogenetic analysis of Caseasauria published by Benson in 2012. [11]

  Caseasauria

In 2015, Romano & Nicosia found a similar position for Euromycter in their most parsimonious analysis including nearly all caseids (to the exclusion of the very fragmentary Alierasaurus ronchi from Sardinia).

Below the most parsimonious phylogenetic analysis published by Romano & Nicosia in 2015. [12]

  Caseasauria

Related Research Articles

<span class="mw-page-title-main">Caseasauria</span> Extinct clade of synapsids

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<span class="mw-page-title-main">Eothyrididae</span> Extinct family of synapsids

Eothyrididae is an extinct family of very primitive, insectivorous synapsids. Only three genera are known, Eothyris, Vaughnictis and Oedaleops, all from the early Permian of North America. Their main distinguishing feature is the large caniniform tooth in front of the maxilla.

<span class="mw-page-title-main">Caseidae</span> Extinct family of synapsids

Caseidae are an extinct family of basal synapsids that lived from the Late Carboniferous to Middle Permian between about 300 and 265 million years ago. Fossils of these animals come from the south-central part of the United States, from various parts of Europe, and possibly from South Africa if the genus Eunotosaurus is indeed a caseid as some authors proposed in 2021. Caseids show great taxonomic and morphological diversity. The most basal taxa were small insectivorous and omnivorous forms that lived mainly in the Upper Carboniferous and Lower Permian, such as Eocasea, Callibrachion, and Martensius. This type of caseid persists until the middle Permian with Phreatophasma and may be Eunotosaurus. During the early Permian, the clade is mainly represented by many species that adopted a herbivorous diet. Some have evolved into gigantic forms that can reach 6–7 metres (20–23 ft) in length, such as Cotylorhynchus hancocki and Alierasaurus ronchii, making them the largest Permian synapsids. Caseids are considered important components of early terrestrial ecosystems in vertebrate history because the numerous herbivorous species in this family are among the first terrestrial tetrapods to occupy the role of primary consumer. The caseids experienced a significant evolutionary radiation at the end of the early Permian, becoming, with the captorhinid eureptiles, the dominant herbivores of terrestrial ecosystems in place of the edaphosaurids and diadectids.

<i>Secodontosaurus</i> Extinct genus of synapsids

Secodontosaurus is an extinct genus of "pelycosaur" synapsids that lived from between about 285 to 272 million years ago during the Early Permian. Like the well known Dimetrodon, Secodontosaurus is a carnivorous member of the Eupelycosauria family Sphenacodontidae and has a similar tall dorsal sail. However, its skull is long, low, and narrow, with slender jaws that have teeth that are very similar in size and shape—unlike the shorter, deep skull of Dimetrodon, which has large, prominent canine-like teeth in front and smaller slicing teeth further back in its jaws. Its unusual long, narrow jaws suggest that Secodontosaurus may have been specialized for catching fish or for hunting prey that lived or hid in burrows or crevices. Although no complete skeletons are currently known, Secodontosaurus likely ranged from about 2 to 2.7 metres (7–9 ft) in length, weighing up to 110 kilograms (250 lb).

Casea is a genus of herbivorous caseid synapsids that lived during the late Lower Permian (Kungurian) in what is now Texas, United States. The genus is only represented by its type species, Casea broilii, named by Samuel Wendell Williston in 1910. The species is represented by a skull associated with a skeleton, a second skull, a partial skull with a better preserved dentition than that of the preceding skulls, and several incomplete postcranial skeletons. Three other Casea species were later erected, but these are considered today to be invalid or belonging to different genera. Casea was a small animal with a length of about 1.20 m and a weight of around 20 kg.

<i>Eothyris</i> Extinct genus of synapsids

Eothyris is a genus of extinct synapsid in the family Eothyrididae from the early Permian. It was a carnivorous insectivorous animal, closely related to Oedaleops. Only the skull of Eothyris, first described in 1937, is known. It had a 6-centimetre-long (2.4-inch) skull, and its total estimated length was 30 centimetres. Eothyris is one of the most primitive synapsids known and is probably very similar to the common ancestor of all synapsids in many respects. The only known specimen of Eothyris was collected from the Artinskian-lower.

<i>Oedaleops</i> Extinct genus of synapsids

Oedaleops is an extinct genus of caseasaur synapsids from the Early Permian of the southwestern United States. Fossils have been found in the Cutler Formation in New Mexico, which dates back to the Wolfcampian stage of the Early Permian. All remains belong to the single known species Oedaleops campi. Oedaleops was closely related to Eothyris, and both are part of the family Eothyrididae. Like Eothyris, it was probably an insectivore.

<i>Cotylorhynchus</i> Extinct genus of synapsids

Cotylorhynchus is an extinct genus of herbivorous caseid synapsids that lived during the late Lower Permian (Kungurian) and possibly the early Middle Permian (Roadian) in what is now Texas and Oklahoma in the United States. The large number of specimens found make it the best-known caseid. Like all large herbivorous caseids, Cotylorhynchus had a short snout sloping forward and very large external nares. The head was very small compared to the size of the body. The latter was massive, barrel-shaped, and ended with a long tail. The limbs were short and robust. The hands and feet had short, broad fingers with powerful claws. The barrel-shaped body must have housed large intestines, suggesting that the animal had to feed on a large quantity of plants of low nutritional value. Caseids are generally considered to be terrestrial, though a semi-aquatic lifestyle has been proposed by some authors. The genus Cotylorhynchus is represented by three species, the largest of which could reach more than 6 m in length. However, a study published in 2022 suggests that the genus may be paraphyletic, with two of the three species possibly belonging to separate genera.

Angelosaurus is an extinct genus of herbivorous caseid synapsids that lived during the late Lower Permian (Kungurian) and early Middle Permian (Roadian) in what is now Texas and Oklahoma in the United States. Like other herbivorous caseids, it had a small head, large barrel-shaped body, long tail, and massive limbs. Angelosaurus differs from other caseids by the extreme massiveness of its bones, particularly those of the limbs, which show a strong development of ridges, processes, and rugosities for the attachment of muscles and tendons. Relative to its body size, the limbs of Angelosaurus were shorter and wider than those of other caseids. The ungual phalanges looked more like hooves than claws. The few known cranial elements show that the skull was short and more robust than that of the other representatives of the group. Angelosaurus is also distinguished by its bulbous teeth with shorter and wider crowns than those of other caseids. Their morphology and the high rate of wear they exhibit suggests a diet quite different from that of other large herbivorous caseids, and must have been based on particularly tough plants. A study published in 2022 suggests that the genus may be paraphyletic, with Angelosaurus possibly only represented by its type species A. dolani.

<i>Ennatosaurus</i> Extinct genus of synapsids

Ennatosaurus is an extinct genus of caseid synapsid that lived during the Middle Permian in northern European Russia. The genus is only represented by its type species, Ennatosaurus tecton, which was named in 1956 by Ivan Antonovich Efremov. The species is known from at least six skulls associated with their lower jaws, as well as from the postcranial bones of several juvenile individuals. Ennatosaurus has the typical caseid skull with a short snout tilted forward and very large external nares. However, it differs from other derived caseids by its postcranial skeleton with smaller proportions compared to the size of the skull. As with other advanced caseids, the teeth of Ennatosaurus were well suited for slicing and cutting vegetation. The presence of a highly developed hyoid apparatus indicates the presence of a massive and mobile tongue, which had to work in collaboration with the palatal teeth during swallowing. With a late Roadian - early Wordian age, Ennatosaurus is one of the last known caseids.

<i>Delorhynchus</i> Extinct genus of reptiles

Delorhynchus is an extinct genus of lanthanosuchoid parareptile known from the late Early Permian Garber Formation of Comanche County, Oklahoma. It contains three species: the type species D. priscus is based on a series of maxillae. The second species to be described, D. cifellii, is known from a larger number of well-preserved skulls and skeletal material. The third species, D. multidentatus, is based on a fragmentary skull with several rows of teeth on its jaw.

Oromycter is an extinct genus of caseid synapsids from the Early Permian of Oklahoma. The sole and type species, Oromycter dolesorum, was named in 2005 by Robert R. Reisz.

<i>Phreatophasma</i> Extinct genus of synapsids

Phreatophasma is an extinct genus of synapsids from the Middle Permian of European Russia. It includes only one species, Phreatophasma aenigmatum, which is itself known from a single femur found in a mine near the town of Belebei in Bashkortostan. Phreatophasma comes from a fossil assemblage that is latest Ufimian to earliest Kazanian in age under the Russian stratigraphic scheme, correlating with the Roadian Age under the international stratigraphic timescale. Because the species is based on a single specimen with few diagnostic anatomical features, uncertainty remains as to where it belongs in tetrapod phylogeny; originally interpreted in 1954 as an enigmatic "theromorph" synapsid by Soviet paleontologist Ivan Yefremov, Phreatophasma was later described as a therapsid incertae sedis by American paleontologist Alfred Romer in 1956 and then as a member of a basal synapsid family called Caseidae starting with Everett C. Olson in 1962. Olson's classification was later supported by Canadian paleontologist Robert Reisz in 1986 and American paleontologist Robert L. Carroll in 1988. Ivakhneneko et al. (1997) and Maddin et al. (2008) both considered Phreatophasma an indeterminate synapsid.

<i>Callibrachion</i>

Callibrachion is an extinct genus of caseid synapsids that lived in east-central France during the Lower Permian (Asselian). The holotype and only known specimen (MNHN.F.AUT490) is represented by an almost complete postcranial skeleton associated with skull fragments discovered at the end of the 19th century in the Permian Autun basin in Saône-et-Loire department, in the Bourgogne-Franche-Comté region. It belongs to an immature individual measuring less than 1.50 m in length. Callibrachion was long considered a junior synonym of the genus Haptodus and classified among the sphenacodontid pelycosaurs. In 2015, a new study found that Callibrachion was a different animal from Haptodus and that it was a caseasaur rather than a sphenacodontid. This was confirmed in 2016 by a cladistic analysis which recovered Callibrachion as a basal caseid. Callibrachion's sharp teeth and unenlarged ribcage indicate that this animal was likely faunivorous.

Ruthenosaurus is an extinct genus of caseid synapsids that lived in what is now southern France during the Early Permian about 285 million years ago. It is known from the holotype MNHN.F.MCL-1 an articulated partial postcranial skeleton. It was collected by D. Sigogneau-Russell and D. Russell in 1970 in the upper part of the M2 Member, Grès Rouge Group, in the Rodez Basin, near the village of Valady, in Occitanie Region. It was first named by Robert R. Reisz, Hillary C. Maddin, Jörg Fröbisch and Jocelyn Falconnet in 2011, and the type species is Ruthenosaurus russellorum.

<i>Alierasaurus</i> Extinct genus of synapsids

Alierasaurus is an extinct genus of caseid synapsid that lived during the early Middle Permian (Roadian) in what is now Sardinia. It is represented by a single species, the type species Alierasaurus ronchii. Known from a very large partial skeleton found within the Cala del Vino Formation, Alierasaurus is one of the largest known caseids. It closely resembles Cotylorhynchus, another giant caseid from the San Angelo Formation in Texas. The dimensions of the preserved foot elements and caudal vertebrae suggest an estimated total length of about 6 or 7 m for Alierasaurus. In fact, the only anatomical features that differ between Alierasaurus and Cotylorhynchus are found in the bones of the feet; Alierasaurus has a longer and thinner fourth metatarsal and it has ungual bones at the tips of the toes that are pointed and claw-like rather than flattened as in other caseids. Alierasaurus and Cotylorhynchus both have very wide, barrel-shaped rib cages indicating that they were herbivores that fed primarily on high-fiber plant material.

Hillary Catherine Maddin is a Canadian paleontologist and developmental biologist known for her work on development in extinct and extant amphibians. She is currently an associate professor in the Department of Earth Sciences at Carleton University.

Martensius is an extinct genus of caseid synapsid from the Early Permian of Germany. The type species is Martensius bromackerensis.

<i>Lalieudorhynchus</i> Extinct genus of synapsids

Lalieudorhynchus is an extinct genus of caseid synapsids that lived during the Guadalupian in what is now the south of France. The genus is only known by its type species, Lalieudorhynchus gandi, which was named in 2022 by Ralf Werneburg, Frederik Spindler, Jocelyn Falconnet, Jean-Sébastien Steyer, Monique Vianey-Liaud, and Joerg W. Schneider. Lalieudorhynchus is represented by a partial postcranial skeleton discovered in the Lodève basin in the central part of the Hérault department in the Occitanie region. It belongs to an individual measuring approximately 3.75 m (12.3 ft) in length. The degree of ossification of its bones, however, indicates that it was a late juvenile or still growing young adult. Based on the internal structure of its bones, the describing authors interpreted Lalieudorhynchus as a semiaquatic animal that may have had a lifestyle similar to that of hippopotamus, spending part of its time in water but returning to land for food, though the idea that caseids were semi-aquatic has been previously contested by other authors. It is geologically one of the youngest known representatives of the caseids. The phylogenetic analysis proposed by Werneburg and colleagues identified Lalieudorhynchus as a derived caseid closely related to the North American species "Cotylorhynchus" hancocki.

References

  1. 1 2 3 4 5 6 Reisz, R.R.; Maddin, H.C.; Fröbisch, J.; Falconnet, J. (2011). "A new large caseid (Synapsida, Caseasauria) from the Permian of Rodez (France), including a reappraisal of "Casea" rutena Sigogneau-Russell & Russell, 1974". Geodiversitas. 33 (2): 227–246. doi:10.5252/g2011n2a2. S2CID   129458820.
  2. ↑ Spindler F., Falconnet J. and Fröbisch J. (2016). Callibrachion and Datheosaurus, two historical and previously mistaken basal caseasaurian synapsids from Europe. Acta Palaeontologica Polonica61. doi : 10.4202/app.00221.2015.
  3. 1 2 3 4 5 Sigoneau-Russell, D.; Russel, D.E. (1974). "Étude du premier caséidé (Reptilia, Pelycosauria) d'Europe occidentale". Bulletin du Muséum national d'Histoire naturelle. Série 3. 38 (230): 145–215.
  4. ↑ Olson, E.C. (1968). "The family Caseidae". Fieldiana Geology. 17: 225–349.
  5. ↑ Kemp, T.S. (2005). The Origin & Evolution of Mammals. Oxford University Press. p. 22. ISBN   978-0198507611.
  6. ↑ Lopez, M.; Gand, G.; Garric, J.; Körner, F.; Schneider, J. (2008). "The playa environments of the Lodève Permian Basin (Languedoc-France)". Journal of Iberian Geology. 34 (1): 29–56.
  7. ↑ Evans, M.E.; Pavlov, V.; Veselovsky, R.; Fetisova, A. (2014). "Late Permian paleomagnetic results from the Lodève, Le Luc, and Bas-Argens Basins (southern France): magnetostratigraphy and geomagnetic field morphology". Physics of the Earth and Planetary Interiors. 237: 18–24. Bibcode:2014PEPI..237...18E. doi:10.1016/j.pepi.2014.09.002.
  8. 1 2 3 Michel, L.A.; Tabor, N.J.; Montañez, I.P.; Schmitz,M.; Davydov, V.I. (2015). "Chronostratigraphy and paleoclimatology of the Lodève Basin, France: evidence for a pan-tropical aridification event across the Carboniferous-Permian boundary". Palaeogeography, Palaeoclimatology, Palaeoecology. 430: 118–131. Bibcode:2015PPP...430..118M. doi: 10.1016/j.palaeo.2015.03.020 .
  9. 1 2 3 4 Werneburg, R.; Spindler, F.; Falconnet, J.; Steyer, J.-S.; Vianey-Liaud, M.; Schneider, J.W. (2022). "A new caseid synapsid from the Permian (Guadalupian) of the Lodève basin (Occitanie, France)" (PDF). Palaeovertebrata. 45 (45(2)-e2): e2. doi:10.18563/pv.45.2.e2. S2CID   253542331.
  10. 1 2 Maddin, H.C.; Sidor, C.A.; Reisz, R.R. (2008). "Cranial anatomy of Ennatosaurus tecton (Synapsida: Caseidae) from the Middle Permian of Russia and the evolutionary relationships of Caseidae". Journal of Vertebrate Paleontology. 28 (1): 160–180. doi:10.1671/0272-4634(2008)28[160:CAOETS]2.0.CO;2. S2CID   44064927.
  11. ↑ Benson, R.B.J. (2012). "Interrelationships of basal synapsids: cranial and postcranial morphological partitions suggest different topologies". Journal of Systematic Palaeontology. 10 (4): 601–624. doi:10.1080/14772019.2011.631042. S2CID   84706899.
  12. ↑ Romano, M.; Nicosia, U. (2015). "Cladistic analysis of Caseidae (Caseasauria, Synapsida): using the gap-weighting method to include taxa based on incomplete specimens". Palaeontology. 58 (6): 1109–1130. doi: 10.1111/pala.12197 . S2CID   86489484.
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