''Orobates'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

diadectid Diadectidae is an extinct family of early tetrapods that lived in what is now North America and Europe during the Late Carboniferous and Early Permian in Asia during the Late Permian. They were the first herbivorous tetrapods, and also the first ...

reptiliomorph Reptiliomorpha (meaning reptile-shaped; in PhyloCode known as ''Pan-Amniota'') is a clade containing the amniotes and those tetrapods that share a more recent common ancestor with amniotes than with living amphibians ( lissamphibians). It was de ...

s that lived during the

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 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

. Its

fossilised A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved i ...

remains were found in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. A combination of primitive and derived traits (i.e. autapomorphic and

plesiomorphic In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorphy, apomorphy, and ...

) distinguish it from all other well-known members of Diadectidae, a family of herbivorous reptiliomorphs. It weighed about 4 kg and appears to have been part of an upland fauna, browsing on high fibre plants. Orobates BW

Locomotion

The

trace fossil A trace fossil, also known as an ichnofossil (; from el, ἴχνος ''ikhnos'' "trace, track"), is a fossil record of biological activity but not the preserved remains of the plant or animal itself. Trace fossils contrast with body fossils, ...

species ''Ichniotherium sphaerodactylum'', from Bromacker in Germany, has been attributed to ''Orobates''. A study in 2015 found that the genus was characterized by a long body and tail, with fairly short legs and a short skull compared to the more derived ''

Diadectes ''Diadectes'' (meaning ''crosswise-biter'') is an extinct genus of large reptiliomorphs or synapsids that lived during the early Permian period (Artinskian-Kungurian stages of the Cisuralian epoch, between 290 and 272 million years ago). ''Diade ...

''. This indicates ''Orobates'' was less specialised for long treks compared to ''Diadectes''. A three-dimensional digital reconstruction of the holotype specimen allowed further analysis of the postcranium. An analysis of the mobility of the hip joint of the reconstructed holotype indicated that its limb function was similar to that of modern

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...

s. A detailed

multidisciplinary Interdisciplinarity or interdisciplinary studies involves the combination of multiple academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fields like sociology, anthropology, psychology, ec ...

study published in 2019 found that ''Orobates'' moved more like modern

caiman A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America f ...

s than salamanders. The study began with the digitization of its

holotype specimen A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

using CT scanning to figure out the range of motion of its

joint A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw ...

s. A digital model of its fossil trackways helped narrow down the possibilities. The researchers also studied the locomotion of four

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extinct, ...

sprawling

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

s using

X-ray motion analysis X-ray motion analysis is a technique used to track the movement of objects using X-rays. This is done by placing the subject to be imaged in the center of the X-ray beam and recording the motion using an image intensifier and a high-speed camera, ...

. The extant tetrapods chosen for the study were

axolotl The axolotl (; from nci, āxōlōtl ), ''Ambystoma mexicanum'', is a paedomorphic salamander closely related to the tiger salamander. Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. I ...

blue-tongued skink Blue-tongued skinks comprise the Australasian genus ''Tiliqua'', which contains some of the largest members of the skink family (Scincidae). They are commonly called blue-tongued lizards or simply blue-tongues or blueys in Australia. As suggeste ...

s, green iguanas, and spectacled caimans. The biomechanical data of the locomotion of the extant tetrapods and the digital models of ''Orobates holotype and fossilized trackways were then used to create a

dynamic simulation Dynamic simulation (or dynamic system simulation) is the use of a computer program to model the time-varying behavior of a dynamical system. The systems are typically described by ordinary differential equations or partial differential equations. ...

. It allowed the researchers to account for physical factors like

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

friction Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: *Dry friction is a force that opposes the relative lateral motion of t ...

, and

balance Balance or balancing may refer to: Common meanings * Balance (ability) in biomechanics * Balance (accounting) * Balance or weighing scale * Balance as in equality or equilibrium Arts and entertainment Film * ''Balance'' (1983 film), a Bulgaria ...

. The simulation was then validated under real-world conditions with a life-sized robot called OroBOT. The researchers tested 512 different

gait Gait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency. Di ...

s and found that ''Orobates'' moved most like a caiman. It had a relatively erect posture and walked with a slight side-to-side motion. A follow-up study focused on the muscle strains occurring within the muscles of the hindlimb in modelled strides at different postures. While results remained inconclusive towards favouring a single posture during locomotion, the overall results did not contradict the previous study based on OroBOT.

References

{{Taxonbar, from=Q772545 Diadectids Artinskian genera Cisuralian tetrapods of Europe Permian Germany Fossils of Germany Fossil taxa described in 2004