Lalieudorhynchus Temporal range: Guadalupian | |
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Partial postcranial skeleton (cast) of Lalieudorhynchus gandi on display at the Musée de Lodève. The sacral vertebrae are not present here. | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | † Caseasauria |
Family: | † Caseidae |
Genus: | † Lalieudorhynchus Werneburg et al., 2022 |
Species | |
Lalieudorhynchus is an extinct genus of caseid synapsids that lived during the Guadalupian (= Middle Permian) 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 . [1]
The genus name is a combination of La Lieude located near the type locality, and "rhynchus", the Latinized form of the Greek "rhynchos" (the nose) sometimes used in the names of caseids. The specific epithet honours Georges Gand who worked on the Lodève basin for decades, notably on the La Lieude footprint slab, and co-organized and promoted the excavation campaigns for this caseid. [1]
Lalieudorhynchus is represented by a partial and disarticulated but well-preserved post-cranial skeleton. The holotype, represented by a series of bones cataloged UM-LIE 02–37, UM-LIE 39–41, UM-LIE 45 and UM-LIE 47, consists of about ten vertebrae (dorsal, sacral and caudal), about fifteen ribs, a complete right scapulocoracoid 50 cm (20 in) long, the dorsal branch of the left ilium, the right and left femora measuring 35.5 cm (14.0 in) long, and several foot bones (an astragalus, two tarsal elements and five phalanges). The total body length of this specimen is estimated at 3.75 m (12.3 ft). The holotype of Lalieudorhynchus shows a mixture of mature and immature characters throughout its skeleton indicating that this specimen was a late juvenile or a still growing young adult at the time of its death. [1] The skull is unknown, but like its closest relatives, it was probably very small compared to the size of the body, triangular-shaped in dorsal view, and terminating anteriorly in a forward-sloping snout with very large external nostrils. The shape of its ribs indicates that Lalieudorhynchus had a barrel-shaped rib cage like other derived caseids. [1] This must have housed large digestive tract suggesting that the animal had to feed on a large quantity of plants with low nutritional value. [2]
Lalieudorhynchus is characterized by several apomorphies. The neural spines of the sacral and anterior caudal vertebrae have a cross section with a very thin keel-like process forwards, which starting above the prezygapophyses and running upwards along the entire vertical edge to the top of the neural spine. The neural spines of the dorsal and caudal vertebrae have their dorsal end slender instead of showing lateral thickening. The first sacral rib has a narrow distal end. The scapulocoracoid has a fossa on the triceps process of the metacoracoid (one of the three bones forming the scapulocoracoid with the procoracoid and the scapula). The foot is characterized by a very large distal tarsus 1 of the same width as the astragalus, with almost all sides slightly concave. [1]
Lalieudorhynchus is also distinguished by a unique combination of characters. Like other caseids, it differs from Ruthenosaurus by its straight neural spines instead of being angled forwards. The middle caudal vertebrae have relatively long centra, elongated below their postzygapophyses, but with low neural arches, unlike Alierasaurus . The three sacral vertebrae and the most anterior caudal vertebra have a short and transversely very wide centrum like in Ruthenosaurus, while these same centra are much narrower in Cotylorhynchus romeri . The neural spine of the first sacral and the first caudal vertebra is very elongated dorsally as in "Cotylorhynchus" hancocki , which is not the case in C. romeri and Ruthenosaurus. A hyposphene is present under the postzygapophyses of the dorsal and caudal vertebrae, a feature previously reported only in C. hancocki. A supraglenoid foramen is present, opening laterally in the supraglenoid fossa and medially in the dorsal part of the subscapular fossa as in "C." hancocki. The shaft of the scapular blade is much wider than that of Alierasaurus. The anteromedial border of the scapula is bulged by the presence of a slightly rounded scapular process, a feature shared with "C." hancocki, "C." bransoni and "Angelosaurus" romeri , but not with C. romeri and Alierasaurus. Two parts of the glenoid fossa have an angle of approximately 130° as in C. bransoni. The femur has a posterior condyle occupying a much more distal position than the anterior condyle, contrary to Ruthenosaurus. The popliteal area of the femur of Lalieudorhynchus is relatively wide with robust grooves, and is much larger and deeper than in C. romeri. The proximal head of the bone is more massive dorso-ventrally than in C. romeri. The femur also has a large pronounced internal trochanter and a little fourth trochanter in its distal half, a feature shared with "C." hancocki, Angelosaurus romeri and A. greeni, and which differs from C. romeri, Angelosaurus dolani, Casea broilii , and Ruthenosaurus. The intercondylar fossa of the femur is very wide, inferring a narrow postero-dorsal condyle, unlike C. romeri and Ruthenosaurus. The astragalus is nearly as broad as long in contrast to most other caseids, but is very similar to that of "C." hancocki. The metatarsal I is robust and enlarged like in Alierasaurus. The phalanges are short and wide. They are shorter than in Alierasaurus. [1]
Rib bone histology of Lalieudorhynchus revealed a bone with a very spongy structure, an extremely thin cortex, and the absence of distinct medullary cavity. These characteristics, also reported in other large caseids such as Cotylorhynchus, would suggest a semiaquatic lifestyle. [3] [1] This hypothesis is however disputed by Kenneth Angielczyk and Christian Kammerer, as well as by Robert Reisz and colleagues based on paleontological and taphonomic data combined with the absence in these large caseids of morphological adaptations to an aquatic lifestyle. However, these authors do not yet provide alternative explanations for the internal bone structure of large caseids. [4] [5] Werneburg and colleagues think that Lalieudorhynchus and large caseids in general, could have had a semiquatic lifestyle comparable to that of hippopotamuses, spending most of their time in water, practicing a kind of subaquatic walking rather than swimming, and possibly returning to land to feed on terrestrial plants. However, paleontologists don't know if Lalieudorhynchus fed on terrestrial and/or aquatic plants. Plant fossils associated with the skeleton of Lalieudorhynchus are identified as terrestrial forms adapted to a dry seasonal climate, while aquatic plants are not present. However, the latter are rarely preserved in Permian sites. Sedimentary analysis of the type locality of Lalieudorhynchus indicates the existence of several potential aquatic habitats. Partially silty claystone beds 15 cm (5.9 in) to 1.8 m (5.9 ft) thick come from suspended-sedimentation in a mass of stagnant water after heavy flooding. Some remains of aquatic arthropods adapted to temporary stagnant waters such as conchostracans and triopsids have been found in these levels. Another possible habitat are river channels reaching 3.5 m (11 ft) to 5 m (16 ft) deep in La Lieude Formation. The presence of rooting at several levels indicates that these channels must not have been filled with flowing water all year round because of the seasonal climate of the time. During the dry season, however, it is likely that masses of stagnant water may have existed in abandoned channels, lakes or ponds, allowing the survival of animals with a more aquatic lifestyle such as the tupilakosaurid dvinosaurs, of which one specimen was associated with the skeleton of Lalieudorhynchus. [1]
The first remains of Lalieudorhynchus were discovered in 2001 by Joerg W. Schneider and Frank Körner in the Salagou stream during geological field mapping in the Lodève basin. Other elements were recovered during excavations carried out between 2004 and 2008 totaling about fifty bones. The size range of the bones indicates that they come from a single individual. The presence of bones of a single and same individual distributed sporadically in a sequence 1.4 m (4.6 ft) thick (with a concentration of bones in a bed of 40 cm (16 in) thick) within horizons with different lithology, could be explained by a decomposition of the carcass in a vegetated area (as suggested by abundant plant remains) alternately exposed and flooded. The bones seem to have been reworked and redeposited several times but over a very short distance and over a very short period of time because the bones are very well preserved. They do not show wear due to transport by water and are not fractured by prolonged exposure to a highly seasonal climate. [1]
The holotype of Lalieudorhynchus comes from the upper part of the La Lieude Formation, in the Lodève basin located in Hérault department, in Occitanie region. The disarticulated skeleton was discovered in strata located approximately 140 m (460 ft) above the base of the formation (which reaches a total of 175 m (574 ft) in thickness). No radiometric dating is available for the La Lieude Formation. A Lopingian (= Upper Permian) age was assigned to it by insects biostratigraphy, radiometric ages and sedimentation rates calculated for the underlying Salagou Formation. Magnetostratigraphic and paleontological data most likely suggest a Guadalupian (= Middle Permian) age. Magnetostratigraphy indicates that the lower part of the La Lieude Formation is no younger than the Illawarra Reversal, a global geomagnetic event dated to the Middle Wordian 266.66 ± 0.76 million years ago. Therefore, this part of the formation would probably have a late Roadian – early Wordian age, while the upper part would have a minimum late Wordian – early Capitanian age. The presence in the lower part of the La Lieude Formation of the ichnogenus Brontopus also indicates a Guadalupian age. Originally discovered at La Lieude, Brontopus has since been found in the Abrahamskraal Formation in South Africa which is radiometrically dated to Wordian and Capitanian. The presumed producers of the Brontopus tracks, the dinocephalian therapsids, are also consistent with a Guadalupian age of the La Lieude Formation because the bones of these animals, discovered in Southern and eastern Africa as well as in Russia, China and Brazil, are exclusively known in Guadalupian deposits. [1] The Wordian - Capitanian age of Lalieudorhynchus makes it one of the last known caseids. With the genera Ennatosaurus and Alierasaurus , it confirms the persistence of caseids during the Guadalupian at least in Europe. [1]
In Guadalupian time, most of the landmasses were united in one supercontinent, Pangea. It was roughly C-shaped: its northern (Laurasia) and southern (Gondwana) parts were connected to the west, but separated to the east by the very large Tethys Sea. [6] A long string of microcontinents, grouped under the name of Cimmeria, divided the Tethys in two : the Paleo-Tethys in the north, and the Neo-Tethys in the south. [7] The Lodève basin was located in the equatorial belt of the time, at the level of the 10th parallel north, and in relation to the Tethys shores, was approximately 400 km inland. [8] [9] Hercynian mounts, with unknown topography, separated the Lodève basin from the Tethys. [9] At that time, the very humid climate which usually characterizes the equatorial climate had been replaced by an extension of the drier tropical climate (with two seasons, dry and wet) toward the regions close to the equator. [8] [10]
The La Lieude Formation is represented by conglomerates, fine to coarse-grained, partly pebbly sandstones, red-brown, partly clayey or fine sandy siltstones, and intercalated silty claystones. These rocks correspond to sands, gravels, and pebbles carried by rivers, and to fluvial silts from floodplains, deposited in a braided river system. There are also several debris flow layers testifying the existence of very heavy rainfall during the wet season. Most of the bones of Lalieudorhynchus come from these debris flow horizons and some from mudflows. These debris flow deposits also contain abundant plant remains represented by numerous lanceolate leaves 5 to 11 cm (2.0 to 4.3 in) in length probably belonging to Plagiozamites, some remains of Podozamites -like coniferophytes, Supaia -like fragments, a few tree trunks up to 2 m (6.6 ft) long and 15 to 20 cm (5.9 to 7.9 in) wide, and smaller plant axes. [1]
Apart from Lalieudorhynchus, the upper part of the Lieude Formation yielded only a vertebral column of a tupilakosaurid temnospondyl, freshwater arthropods (conchostracans and triopsids), insect wings (Odonata), and indeterminable footprints. [1] Other elements of the fauna of the La Lieude Formation are present on the La Lieude slab, located towards the base of the formation, which exposes numerous tetrapod trackways. Many tetrapod ichnospecies [nb 1] have been named from this site. The taxonomic and morphological review of these footprints distinguished four valid ichnospecies and identified their probable producers: Brontopus giganteus and B. antecursor, which very probably represents dinocephalian therapsids (respectively a Tapinocephalia and an Anteosauridae), Merifontichnus thalerius, which corresponds to footprints of a moradisaurin captorhinid eureptile, and Pachypes ollieri, which would belong to a pareiasauromorpha Nycteroleteridae. [11] [12] [13]
Phylogenetic analysis by Wernebug and colleagues identified Lalieudorhynchus gandi as one of the most derived caseids and the sister taxon to the North American species "Cotylorhynchus" hancocki . These two taxa form a clade characterized by the presence of a hyposphene, as well as by the presence and position of the supraglenoid foramen. This clade forms with "Cotylorhynchus" bransoni an apical clade characterized by closely spaced postzygapophyses. This analysis also suggests that the genera Angelosaurus and Cotylorhynchus (each composed of three species) would be paraphyletic, taxa other than their type species may belong to different genera. [1]
Below is the cladogram published by Werneburg and colleagues in 2022.
Caseidae |
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Petrolacosaurus is an extinct genus of diapsid reptile from the late Carboniferous period. It was a small, 40-centimetre (16 in) long reptile, and one of the earliest known reptile with two temporal fenestrae. This means that it was at the base of Diapsida, the largest and most successful radiation of reptiles that would eventually include all modern reptile groups, as well as dinosaurs and other famous extinct reptiles such as plesiosaurs, ichthyosaurs, and pterosaurs. However, Petrolacosaurus itself was part of Araeoscelida, a short-lived early branch of the diapsid family tree which went extinct in the mid-Permian.
Caseasauria is one of the two main clades of early synapsids, the other being the Eupelycosauria. Caseasaurs are currently known only from the Late Carboniferous and the Permian, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae, and the large, herbivorous Caseidae. These two groups share a number of specialised features associated with the morphology of the snout and external naris.
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.
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.
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.
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.
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.
Qianosuchus is an extinct genus of aquatic poposauroid archosaur from the middle Triassic (Anisian) Guanling Formation of Pan County, China. It is represented by two nearly complete skeletons and a crushed skull preserved in the limestone. Qianosuchus was at least 3 metres long, and had several skeletal adaptations which indicate a semi-marine lifestyle, similar to modern-day saltwater crocodiles. These adaptations have not been seen in any other archosaur from the Triassic.
Tapinocaninus is an extinct genus of therapsids in the family Tapinocephalidae, of which it is the most basal member. Only one species is known, Tapinocaninus pamelae. The species is named in honor of Rubidge's mother, Pam. Fossils have been found dating from the Middle Permian.
Tetragonias is an extinct genus of dicynodont from the Anisian Manda Beds of Tanzania. With tetra meaning “four,” and goni meaning “angle,” the name references the square shape of the Tetragonias skull when viewed dorsally. Not to be confused with the plant Tetragonia,Tetragonias were dicynodont anomodonts discovered in the late 1960s by paleontologist A. R. I. Cruickshank in the Manda Formation. Only the type species, T. njalilus, has been recognized.
Heleosaurus scholtzi is an extinct species of basal synapsids, known as pelycosaurs, in the family of Varanopidae during the middle Permian. At first H. scholtzi was mistakenly classified as a diapsid. Members of this family were carnivorous and had dermal armor, and somewhat resembled monitor lizards. This family was the most geologically long lived, widespread, and diverse group of early amniotes. To date only two fossils have been found in the rocks of South Africa. One of these fossils is an aggregation of five individuals.
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.
Euromycter is an extinct genus of caseid synapsids that lived in what is now southern France during the Early Permian 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, 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. 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.
Pampaphoneus is an extinct genus of carnivorous dinocephalian therapsid belonging to the family Anteosauridae. It lived 268 to 265 million years ago during the Wordian age of the Guadalupian period in what is now Brazil. Pampaphoneus is known by an almost complete skull with the lower jaw still articulated, discovered on the lands of the Boqueirão Farm, near the city of São Gabriel, in the state of Rio Grande do Sul. A second specimen from the same locality was reported in 2019 and 2020 but has not yet been described. It is composed of a skull associated with postcranial remains. It is the first South American species of dinocephalian to have been described. The group was previously known in South America only by a few isolated teeth and a jaw fragment reported in 2000 in the same region of Brazil. Phylogenetic analysis conducted by Cisneros and colleagues reveals that Pampaphoneus is closely related to anteosaurs from European Russia, indicating a closer faunal relationship between South America and Eastern Europe than previously thought, thus promoting a Pangea B continental reconstruction.
Ichthyovenator is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the Grès supérieurs Formation of the Savannakhet Basin, the first of which were found in 2010, consisting of a partial skeleton without the skull or limbs. This specimen became the holotype of the new genus and species Ichthyovenator laosensis, and was described by palaeontologist Ronan Allain and colleagues in 2012. The generic name, meaning "fish hunter", refers to its assumed piscivorous lifestyle, while the specific name alludes to the country of Laos. In 2014, it was announced that more remains from the dig site had been recovered; these fossils included teeth, more vertebrae (backbones) and a pubic bone from the same individual.
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.
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