''Largocephalosaurus'' 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 ...
of
basal saurosphargid, a
marine reptile
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment.
The earliest marine reptile mesosaurus (not to be confused with mosasaurus), arose in the Permian period during the ...
known from the
Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...
(
Anisian
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...
age)
Guanling Formation
The Guanling Formation is a Middle Triassic (Anisian or Pelsonian in the regional chronostratigraphy) geologic formation in southwestern China.
Description
The formation encompasses two members. The first member is primarily calcareous mudston ...
of
Yunnan
Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...
and
Guizhou
Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to t ...
Provinces, southwestern
China
China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...
. It contains a
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
, ''Largocephalosaurus polycarpon'', and a second species ''L. qianensis''.
''L. polycarpon'' was initially interpreted as an
eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...
n sauropterygian closely related to European
pachypleurosaur
left, 220px, '' Pachypleurosaurus''
Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , w ...
s and
nothosaurid
Nothosauridae are an extinct family of carnivorous aquatic sauropterygian reptiles from the Triassic time period of China, France, Germany, Israel, Italy, Netherlands, Russia, Switzerland, and northern Africa.
Phylogeny
The cladogram shown bel ...
s.
[ However following additional preparation of the ]postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...
l skeleton and the discovery of a second better known species ''L. qianensis'', Li ''et al.'' (2014) reinterpreted ''Largocephalosaurus'' as a basal member of the family Saurosphargidae
Saurosphargidae is an extinct family of marine reptiles known from the early Middle Triassic (Anisian stage) of Europe and China.
The type species of the family is '' Saurosphargis volzi'', named by Friedrich von Huene in 1936 based on a single ...
and a close relative of ''Saurosphargis
''Saurosphargis'' is an extinct genus of a basal marine reptile, saurosphargid, known from the Middle Triassic (Anisian age) of southwestern Poland and eastern Netherlands. It contains a single species, ''Saurosphargis volzi''.
Discovery
' ...
'' and '' Sinosaurosphargis''. According to Li ''et al.'' (2014), saurosphargids did not belong to Sauropterygia
Sauropterygia ("lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became ...
, although they were closely related to it, forming its 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 t ...
.[
]
Discovery
The type species of ''Largocephalosaurus'', ''L. polycarpon'' is known only from 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 several ...
WIGM SPC V 1009 a nearly complete and articulated 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, the ...
and skeleton
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
missing most of its tail and measuring more than in length, housed at the Wuhan Institute of Geology and Mineral Recourses. SPC V 1009 was collected from Member II of the Guanling Formation
The Guanling Formation is a Middle Triassic (Anisian or Pelsonian in the regional chronostratigraphy) geologic formation in southwestern China.
Description
The formation encompasses two members. The first member is primarily calcareous mudston ...
, dating to the Pelsonian substage of the mid-late Anisian
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until million years ago. The Anisian Age succeeds the Olenekian Age (part of the Lower Triassic Ep ...
stage of the early Middle Triassic
In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...
, about 243 million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...
, at Luoping County
Luoping County () is located in Qujing City, in eastern Yunnan province, China, bordering Guizhou province to the east and the Guangxi Zhuang Autonomous Region to the southeast.
The county of Luoping in eastern Yunnan is noted for its springtim ...
of Yunnan Province
Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the C ...
.[
While ''L. polycarpon'' was being studied at the WIGM, three specimens of what was later named ''L. qianensis'' were prepared at the Geological Museum of Peking University and the ]Institute of Vertebrate Paleontology and Paleoanthropology The Institute of Vertebrate Paleontology and Paleoanthropology (IVPP; ) of China is a research institution and collections repository for fossils, including many dinosaur and pterosaur specimens (many from the Yixian Formation). As its name suggest ...
. These three specimens were collected in 2008 about 100 km northeast of the type locality of ''L. polycarpon'' at Xinmin District of Panxian County, southwestern Guizhou Province
Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to the ...
. They, like SPC V 1009, came from Member II of the Guanling Formation, dating to the late Anisian. Out of these specimens, IVPP V 15638, a nearly complete skeleton exposed in view from below with only the back of the tail missing, was chosen to represent the holotype of ''L. qianensis''. The other two specimen are referable to ''L. qianensis'' and include GMPKU-P-1532-A, a skull with a neck vertebra
In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
in view from above, and GMPKU-P-1532-B, an incomplete postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...
l skeleton in view from above, with the back portion of the mandible
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 tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...
preserved, but missing most of the tail.[
All specimens of ''Largocephalosaurus'' came from the ]Lagerstätte
A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...
discovered during a 2007 geological mapping project with a diverse record of marine life called Luoping Biota, that yielded, apart from ''Largocephalosaurus'', various invertebrates, fish, basal ichthyosaur
Ichthyosaurs (Ancient Greek for "fish lizard" – and ) are large extinct marine reptiles. Ichthyosaurs belong to the order known as Ichthyosauria or Ichthyopterygia ('fish flippers' – a designation introduced by Sir Richard Owen in 1842, altho ...
s, ''Atopodentatus
''Atopodentatus'' is an extinct genus of basal sauropterygian known from the early Middle Triassic (Pelsonian substage, Anisian to Ladinian stage) of Luoping County, Yunnan Province, southwestern China. It contains a single species, ''Atopodenta ...
'', the advanced saurosphargid '' Sinosaurosphargis'', and several species of eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...
n, including both pachypleurosaur
left, 220px, '' Pachypleurosaurus''
Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , w ...
s and nothosaurid
Nothosauridae are an extinct family of carnivorous aquatic sauropterygian reptiles from the Triassic time period of China, France, Germany, Israel, Italy, Netherlands, Russia, Switzerland, and northern Africa.
Phylogeny
The cladogram shown bel ...
s.
Etymology
''Largocephalosaurus'' was first described and named by Long Cheng, Xiaohong Chen, Xiongwei Zeng and Yongjian Cai in 2012
File:2012 Events Collage V3.png, From left, clockwise: The passenger cruise ship Costa Concordia lies capsized after the Costa Concordia disaster; Damage to Casino Pier in Seaside Heights, New Jersey as a result of Hurricane Sandy; People gather ...
with the type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
''Largocephalosaurus polycarpon''. The generic name is said to be derived from 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 ...
''largus'', meaning "large", and ''cephalus'', meaning "head", and from Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''sauros'', meaning "lizard", a common suffix for genus names of 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 ...
reptile
Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s. In classical Latin, the proper word for "head" is ''caput'', while in ancient Greek ''kephalē'' (κεφαλή) was used for "head".[Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie.'' Oxford: Clarendon Press.] ''Kephalos'' (Κέφαλος) was the first name of various Greek mythological and historical figures that was rendered in Latin as ''Cephalus''.[Lewis, C.T. & Short, C. (1879). ''A Latin dictionary founded on Andrews' edition of Freund's Latin dictionary.'' Oxford: Clarendon Press.]
The specific name Specific name may refer to:
* in Database management systems, a system-assigned name that is unique within a particular database
In taxonomy, either of these two meanings, each with its own set of rules:
* Specific name (botany), the two-part (bino ...
''polycarpon'' is said to be derived from Latin ''poly'', meaning "many", plus "carpon", meaning "ossified
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by Cell (biology), cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes ...
carpal
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...
s", in reference to the eleven carpal ossification
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
s the forelimb of ''L. polycarpon'' shows, resulting in the unique hand bone formula of 2-3-4-5-5.[ In classical Latin the proper word for "many" is ''multus'',] while in ancient Greek they used the word ''polys'' (πολύς).
A second species ''L. qianensis'' was named by Chun Li, Da-Yong Jiang, Long Cheng, Xiao-Chun Wu and Olivier Rieppel in 2014
File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...
. Its specific name is derived from ''Qian'', a shortened alternative spelling for Guizhou
Guizhou (; formerly Kweichow) is a landlocked province in the southwest region of the People's Republic of China. Its capital and largest city is Guiyang, in the center of the province. Guizhou borders the autonomous region of Guangxi to t ...
, plus the Latin suffix ''-ensis'' meaning "from", in reference to the different occurrence of the species - while the specimens of ''L. qianensis'' were discovered in Guizhou Province, the only known specimen of ''L. polycarpon'' came from the neighboring Yunnan
Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...
Province.[
]
Description
''Largocephalosaurus'' was a relatively large saurosphargid, with the type specimen of the second species ''L. qianensis'' measuring up to in total body length. It is a basal saurosphargid, less modified morphologically from the archetypal diapsid
Diapsids ("two arches") are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The group first appeared about three hundred million years ago ...
reptile compared to advanced saurosphargids like '' Sinosaurosphargis''.[ However, even in its original description that interpreted it as an ]eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...
n sauropterygian, several traits later identified as saurosphargid were noted. These include back vertebrae that show elongated, distally expanded transverse projections, and its broadened and flattened chest rib
In vertebrate anatomy, ribs ( la, costae) are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the chest, enabling the lungs to expand and thus facilitate breathing by expanding the ches ...
s.[ Yet, ''Largocephalosaurus'' unlike other saurosphargids retains an elongate body shape, a well-developed supra]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, ...
, an oval suborbital fenestra
A fenestra (fenestration; plural fenestrae or fenestrations) is any small opening or pore, commonly used as a term in the biological sciences. It is the Latin word for "window", and is used in various fields to describe a pore in an anatomical st ...
(although much reduced compared to non-saurosphargids) and an incomplete dorsal osteoderm
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amp ...
carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
. Additionally, the advanced saurosphargids ''Saurosphargis'' and ''Sinosaurosphargis'' have broader and flatter rib baskets, and also transverse projections of back vertebrae and proximal portions of chest ribs that are much more robust than in ''Largocephalosaurus'', being much wider than the spacing between them. Other differences include: the presence of three or four teeth on the premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has b ...
, and its exclusion from the external nostril
A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...
outline; an elongated frontal bone
The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, par ...
back-side facing projection; the presence of a row of large osteoderm
Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amp ...
s on the top of the neural spines, in the midline of the partial osteoderm shield; and similarly rounded 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 ...
and pubis bone
In vertebrates, the pubic region ( la, pubis) is the most forward-facing (ventral and anterior) of the three main regions making up the coxal bone. The left and right pubic regions are each made up of three sections, a superior ramus, inferior ra ...
with the coracoid and the obturator fenestra present and open (respectively).[
Due to the fact that 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 several ...
skeleton of ''L. polycarpon'' is still only partially prepared, Li ''et al.'' (2014) refrained from providing a revised description for it. Nevertheless, at least 9 morphological differences from the second the species ''L. qianensis'' were observed. These include the paired parietal bone
The parietal bones () are two bones in the Human skull, skull which, when joined at a fibrous joint, form the sides and roof of the Human skull, cranium. In humans, each bone is roughly quadrilateral in form, and has two surfaces, four borders, an ...
, the large pineal foramen
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythm ...
, the oval eye-sockets, and the presence of 33 presacral vertebrae (9 neck and 24 back vertebrae) and two sacral vertebrae
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
, in ''L. qianensis''. Additionally, a distinct palatal fossa exists on the upper surface of palatine bone
In anatomy, the palatine bones () are two irregular bones of the facial skeleton in many animal species, located above the uvula in the throat. Together with the maxillae, they comprise the hard palate. (''Palate'' is derived from the Latin ''pa ...
in ''L. qianensis'', and the retroarticular process is very short. The back osteoderms of ''L. qianensis'' are elongated granular in shape, and covering the sides of body. Finally, its shoulder portion of the chest ribs is broadened in a hook-like projection, while lacking the crest on its upper surface like the one seen in ''L. polycarpon''.[
]
Phylogeny
''Largocephalosaurus'' was first included in a 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 ...
in its original description. Due to the lack of preparation of the holotype, especially of the postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...
l portion, and the fact that no other saurosphargids or stem sauropterygia
Sauropterygia ("lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became ...
ns (like ''Eusaurosphargis
''Eusaurosphargis'' is an extinct genus of a diapsid reptile, known from the Middle Triassic (Anisian and Ladinian age) Besano Formation of northern Italy and Prosanto Formation of south-eastern Switzerland. It contains a single species, ''Eusa ...
'' and ''Helveticosaurus
''Helveticosaurus'' is an extinct genus of diapsid marine reptile known from the Middle Triassic (Anisian-Ladinian boundary) of southern Switzerland. It contains a single species, ''Helveticosaurus zollingeri'', known from the nearly complet ...
'') were included, ''L. polycarpon'' was recovered in a position most closely related to ''Wumengosaurus
''Wumengosaurus'' is an extinct aquatic reptile from the Middle Triassic (late Anisian stage) Guanling Formation of Guizhou, southwestern China. It was originally described as a basal eosauropterygian and usually is recovered as such by phyloge ...
'' within Eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...
, basal to the European pachypleurosaur
left, 220px, '' Pachypleurosaurus''
Pachypleurosauria is an extinct clade of primitive sauropterygian reptiles that vaguely resembled aquatic lizards, and were limited to the Triassic period. They were elongate animals, ranging in size from , w ...
s and nothosaurid
Nothosauridae are an extinct family of carnivorous aquatic sauropterygian reptiles from the Triassic time period of China, France, Germany, Israel, Italy, Netherlands, Russia, Switzerland, and northern Africa.
Phylogeny
The cladogram shown bel ...
s. However, following additional preparation of the postcranial skeleton and the discovery of a second better known species ''L. qianensis'', Li ''et al.'' (2014) presented an analysis which includes ''Eusaurosphargis'', ''Helveticosaurus'' and all known saurosphargid species. The following cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
is simplified after their results. The removal / inclusion of Ichthyopterygia
Ichthyopterygia ("fish flippers") was a designation introduced by Sir Richard Owen in 1840 to designate the Jurassic ichthyosaurs that were known at the time, but the term is now used more often for both true Ichthyosauria and their more primitiv ...
was found to affect the topology
In mathematics, topology (from the Greek language, Greek words , and ) is concerned with the properties of a mathematical object, geometric object that are preserved under Continuous function, continuous Deformation theory, deformations, such ...
the most - switching the positions of the ''Eusaurosphargis''+''Helveticosaurus'' and Thalattosauriformes clades, and altering the positions of several taxa within Eosauropterygia
Sauropterygia (" lizard flippers") is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria bec ...
, which are not shown.[
]
Notes
References
{{Taxonbar, from=Q6489300
Middle Triassic reptiles of Asia
Anisian life
Triassic China
Fossils of China
Paleontology in Guizhou
Guanling Formation
Fossil taxa described in 2012
Fossil taxa described in 2014
Prehistoric reptile genera