''Euromycter'' is an
extinct genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
caseid
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 (Texas, Oklaho ...
synapsid
Synapsids + (, 'arch') > () "having a fused arch"; synonymous with ''theropsids'' (Greek, "beast-face") are one of the two major groups of animals that evolved from basal amniotes, the other being the sauropsids, the group that includes reptil ...
s that lived in what is now southern
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
during the
Early Permian (late
Artinskian
In the geologic timescale, the Artinskian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Artinskian likely lasted between and million years ago (Ma) according to the most recent revision of th ...
) about 285 million years ago. The
holotype
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 sever ...
and only known specimen of ''Euromycter'' (
MNHN.F.MCL-2) includes the complete
skull
The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...
with
lower jaw
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
s and
hyoid apparatus
The hyoid apparatus is the collective term used in veterinary anatomy for the bones which suspend the tongue and larynx. It consists of pairs of stylohyoid, thyrohyoid, epihyoid and ceratohyoid bones, and a single basihyoid bone. The hyoid appara ...
, six
cervical vertebrae with
proatlas, anterior part of
interclavicle
An interclavicle is a bone which, in most tetrapods, is located between the clavicles. Therian mammals (marsupials and placentals) are the only tetrapods which never have an interclavicle, although some members of other groups also lack one. In t ...
, partial right
clavicle
The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the r ...
, right posterior
coracoid
A coracoid (from Greek κόραξ, ''koraks'', raven) is a paired bone which is part of the shoulder assembly in all vertebrates except therian mammals (marsupials and placentals). In therian mammals (including humans), a coracoid process is prese ...
, distal head of right
humerus, left and right
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
, left and right
ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of t ...
, 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
Aveyron (; oc, Avairon; ) is a department in the region of Occitania, Southern France. It was named after the river Aveyron. Its inhabitants are known as ''Aveyronnais'' (masculine) or ''Aveyronnaises'' (feminine) in French. The inhabitants ...
),
Rodez Basin. It was first assigned to the species ''"
Casea
''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 Willisto ...
" 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.
[Spindler F., Falconnet J. and Fröbisch J. (2016). ''Callibrachion'' and ''Datheosaurus'', two historical and previously mistaken basal caseasaurian synapsids from Europe. ''Acta Palaeontologica Polonica'' 61. .]
Etymology
The generic name refers to the location of the taxon in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
, and “mycter” = nose, refers to the enlarged external naris that characterizes the caseids.
[ The species epithet refers to ]ruteni
The Ruteni were a Gallic tribe dwelling in the southern part of the Massif Central, around present-day Rodez, during the Iron Age and the Roman period.
Name
They are mentioned as ''Rutenos'' by Caesar (mid-1st c. BC), ''R̔outēnoì'' (Ῥου ...
(Les Rutènes in French) the Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
name of the Gallic tribe that lived in the Rodez area.
Description
The skull is well-preserved but has suffered of a slight flattening as a result of a tectonic
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...
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
The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity.
A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly separ ...
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. 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 worked in conjunction with a tough and massive muscular tongue
The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste ...
as indicated by the presence of a very well-developed hyoid apparatus
The hyoid apparatus is the collective term used in veterinary anatomy for the bones which suspend the tongue and larynx. It consists of pairs of stylohyoid, thyrohyoid, epihyoid and ceratohyoid bones, and a single basihyoid bone. The hyoid appara ...
.
Characteristically, ''Euromycter'' shows an unusually broad skull, large temporal fenestra
An infratemporal fenestra, also called the lateral temporal fenestra or simply temporal fenestra, is an opening in the skull behind the orbit in some animals. It is ventrally bordered by a zygomatic arch. An opening in front of the eye sockets ...
, and lack of expansion of the axial neural spine
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
. It can be distinguished from other caseids by the presence of a supernumerary
Supernumerary means "exceeding the usual number".
Supernumerary may also refer to:
* Supernumerary actor, a performer in a film, television show, or stage production who has no role or purpose other than to appear in the background, more commonl ...
blade-like intranarial bone located posteromedially to the septomaxilla, proportional differences in forelimb and manus, presence of an accessory proximal articulation between metacarpals
In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones ar ...
3 and 4, medial recurvature of metacarpal, and its manual phalangeal formula
The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones ...
of 2-3-4-4-3.[
]
Stratigraphic range
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
A sabkha ( ar, سبخة) is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal p ...
) under a semi-arid, hot climate.[ The age of the Grès Rouge Group is uncertain but it is regarded as contemporaneous to the Saxonian Group of the neighbouring ]Lodève
Lodève (; oc, Lodeva ) is a commune in the département of Hérault, in the Occitanie region in southern France. It is a sub-prefecture of the department. The derivation of the city's name is from Gaulish ''Luteva'', composed of lut-, swamp, ...
basin, where radiometric
Radiometry is a set of techniques for measuring electromagnetic radiation, including visible light. Radiometric techniques in optics characterize the distribution of the radiation's power in space, as opposed to photometric techniques, which ch ...
and magnetostratigraphic data suggested previously an age between the late Sakmarian
In the geologic timescale, the Sakmarian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Sakmarian lasted between 293.52 and million years ago (Ma). It was preceded by the Asselian and followed by t ...
(middle of the Early Permian) and the early Lopingian
The Lopingian is the uppermost series/last epoch of the Permian. It is the last epoch of the Paleozoic. The Lopingian was preceded by the Guadalupian and followed by the Early Triassic.
The Lopingian is often synonymous with the informal terms l ...
(early Late Permian).[ However, new ]chronostratigraphic
Chronostratigraphy is the branch of stratigraphy that studies the ages of rock strata in relation to time.
The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geologic ...
and magnetostratigraphic data for the Saxonian Group indicate an age between the Artinskian
In the geologic timescale, the Artinskian is an age or stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Artinskian likely lasted between and million years ago (Ma) according to the most recent revision of th ...
(for the Rabejac Formation and the Octon Member of the Salagou Formation) and the late Roadian
In the geologic timescale, the Roadian is an age or stage of the Permian. It is the earliest or lower of three subdivisions of the Guadalupian Epoch or Series. The Roadian lasted between and million years ago (Ma). It was preceded by the ...
-Wordian
In the geologic timescale, the Wordian is an age or stage of the Permian. It is the middle of three subdivisions of the Guadalupian Epoch or Series. The Wordian lasted between and million years ago (Ma). It was preceded by the Roadian and f ...
and possibly early Capitanian
In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian Epoch or Series. The Capitanian lasted between and million years ago. It was preceded by ...
(for La Lieude Formation). 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 palynomorph
Palynology is the "study of dust" (from grc-gre, παλύνω, palynō, "strew, sprinkle" and ''-logy'') or of "particles that are strewn". A classic palynologist analyses particulate samples collected from the air, from water, or from deposit ...
s, conchostracans, and a 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 t ...
footprints assemblage equivalent to that of the Viala Formation of the Lodève basin. The lower part of the Viala Formation yielded a radiometric age of 290.96 ± 0.19 Ma corresponding to the late Sakmarian. 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
Saint-Affrique (; Languedocien: ''Sant Africa'') is a commune in the Aveyron department in Southern France.
History
Saint-Affrique grew in the 6th century around the tomb of St. Africain, bishop of Comminges. In the 12th century a fortre ...
basin in southern Aveyron
Aveyron (; oc, Avairon; ) is a department in the region of Occitania, Southern France. It was named after the river Aveyron. Its inhabitants are known as ''Aveyronnais'' (masculine) or ''Aveyronnaises'' (feminine) in French. The inhabitants ...
). Above the Rabéjac Formation, the lower two-thirds of the Octon Member of the Salagou Formation yielded four tuff
Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...
horizons radiometrically dated. The oldest tuff horizon provided an age of 284.40 ± 0.07 Ma corresponding to the latest Artinskian. 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. 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.
Discovery
During a prospecting survey carried out in the Permian red sandstones outcropping in badlands
Badlands are a type of dry terrain where softer sedimentary rocks and clay-rich soils have been extensively eroded."Badlands" in ''Chambers's Encyclopædia''. London: George Newnes, 1961, Vol. 2, p. 47. They are characterized by steep slopes, m ...
on the western flank of the Cayla Hill (commune
A commune is an alternative term for an intentional community. Commune or comună or comune or other derivations may also refer to:
Administrative-territorial entities
* Commune (administrative division), a municipality or township
** Communes of ...
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 permits 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
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 ( Texas, ...
pelycosaur
Pelycosaur ( ) is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term ''mammal-like reptile'' had been used, and pelycosaur was considered an order, but this is ...
s. 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'' 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 Willisto ...
'', ''Casea rutena''. This animal was celebrated as the first caseid found in Western Europe
Western Europe is the western region of Europe. The region's countries and territories vary depending on context.
The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the ancient Mediterranean ...
, making of this species a geographical link with other specimens of the family that were previously known only in the south central United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...
(Texas
Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
and Oklahoma) and in the northern European Russia.
In 2008, a phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis of Caseidae demonstrates the paraphyly of the genus ''Casea'', the French species representing a distinct unnamed genus. 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''.[
]
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
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to a derive clade containing '' Ennatosaurus tecton'', '' Cotylorhynchus romeri'' and '' Angelosaurus dolani''.
Below the first phylogenetic analysis
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
of Caseidae published by Maddin et al. in 2008.
A phylogenetic analysis made by Benson shows a similar position for ''Euromycter'' (again regarded as “''Casea''” ''rutena'').
Below the phylogenetic analysis
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
of Caseasauria published by Benson in 2012.
In 2015, Romano & Nicosia found a similar position for ''Euromycter'' in their most parsimonious
Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...
analysis including nearly all caseids (to the exclusion of the very fragmentary '' Alierasaurus ronchi'' from Sardinia
Sardinia ( ; it, Sardegna, label=Italian, Corsican and Tabarchino ; sc, Sardigna , sdc, Sardhigna; french: Sardaigne; sdn, Saldigna; ca, Sardenya, label=Algherese and Catalan) is the second-largest island in the Mediterranean Sea, after ...
).
Below the most parsimonious phylogenetic analysis published by Romano & Nicosia in 2015.
References
{{Taxonbar, from=Q5411994
Caseasaurs
Prehistoric synapsid genera
Fossil taxa described in 2011
Fossils of France