''Parasuchus'' is an
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
basal phytosaur known from the
Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...
(late
Carnian
The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...
to early
Norian
The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...
stage) of
Andhra Pradesh
Andhra Pradesh (ISO 15919, ISO: , , AP) is a States and union territories of India, state on the East Coast of India, east coast of southern India. It is the List of states and union territories of India by area, seventh-largest state and th ...
and
Madhya Pradesh
Madhya Pradesh (; ; ) is a state in central India. Its capital is Bhopal and the largest city is Indore, Indore. Other major cities includes Gwalior, Jabalpur, and Sagar, Madhya Pradesh, Sagar. Madhya Pradesh is the List of states and union te ...
,
India
India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
. At its most restricted definition, ''Parasuchus'' contains a single species, ''Parasuchus hislopi''.
[ ''Parasuchus hislopi'' is one of several species belonging to a basal grade of phytosaurs, typified by the genus '' Paleorhinus''. Historically, ''Paleorhinus'' has been known from better-described fossils, and many species have been lumped into that genus. ''Parasuchus hislopi'', despite being described earlier than ''Paleorhinus'', was considered an undiagnostic chimera until new ]neotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
fossils were described in the late 1970s. ''Parasuchus hislopi'' and the two unambiguously valid species of ''Paleorhinus'' (''P. bransoni'' and ''P. angustifrons'') are all closely related; some authors have historically described them all under the species ''Paleorhinus'', while others place the two ''Paleorhinus'' species into ''Parasuchus'' according to the principle of priority
Priority is a principle in Taxonomy (biology), biological taxonomy by which a valid scientific name is established based on the oldest available name. It is a decisive rule in Botanical nomenclature, botanical and zoological nomenclature to recogn ...
.
History
The name ''Parasuchus'' was first used by Thomas Henry Huxley (1870) in a faunal list. Since a diagnosis wasn't provided, it would have been considered a ''nomen nudum
In Taxonomy (biology), taxonomy, a ''nomen nudum'' ('naked name'; plural ''nomina nuda'') is a designation which looks exactly like a scientific name of an organism, and may have originally been intended to be one, but it has not been published ...
'' at the time. Richard Lydekker
Richard Lydekker (; 25 July 1849 – 16 April 1915) was a British naturalist, geologist and writer of numerous books on natural history. He was known for his contributions to zoology, paleontology, and biogeography. He worked extensively in cata ...
(1885) formally described and named ''P. hislopi'', and proposed the family name Parasuchidae. However, Lydekker's description was based on a chimeric syntype, combining fossils from multiple unrelated reptiles: a rhynchosaurian basicranium mixed with the partial snout of a phytosaur, scutes and some teeth. Friedrich von Huene (1940) identified the basicranium as belonging to '' Paradapedon huxleyi'' (now known as '' Hyperodapedon huxleyi'') and the phytosaurian material to a newly named species, "aff." '' Brachysuchus maleriensis''. Later, Edwin Harris Colbert (1958) designated all the Indian parasuchian material as '' Phytosaurus maleriensis'' while Gregory (1962) considered the material undiagnostic.
Sankar Chatterjee (1978) described many complete remains of the Indian parasuchian and showed that it is not assignable either to '' Brachysuchus'' (which is closely related to or synonymous with '' Angistorhinus''), or to '' Phytosaurus'' (a dubious name, probably the senior synonym
In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently.
...
of '' Nicrosaurus''). He argued that the rhynchosaur basicranium qualifies as neither the holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
of ''P. hislopi'', nor the lectotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
of ''Paradapedon huxleyi.'' He re-introduced ''P. hislopi'', based on Lydekker's snout fossil and new well-preserved material. To avoid additional confusion, the nondiagnostic holotype of ''P. hislopi'' was replaced by a neotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
(ISI R 42) with approval from the ICZN (Opinion 2045) following the application of Chatterjee (2001).
Fossil material
The partial premaxillary rostrum
Rostrum may refer to:
* Any kind of a platform for a speaker:
**dais
**pulpit
** podium
* Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects
* Rostrum (ship), a form of bow on naval ...
(snout) originally described by Lydekker, GSI H 20/11, was chosen as the lectotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
of ''Parasuchus hislopi'' by Sankar Chatterjee. GSI H 20/11 was collected from the Lower Maleri Formation ( Pranhita–Godavari Basin), near the Maleri village of Adilabad district, Andhra Pradesh. The lectotype was rendered obsolete when neotype fossils were approved for the genus in 2003.
Sankar Chatterjee later described more comprehensive remains from the Lower Maleri Formation, as well as one nearly complete skull
The skull, or cranium, is typically a bony enclosure around the brain of a vertebrate. In some fish, and amphibians, the skull is of cartilage. The skull is at the head end of the vertebrate.
In the human, the skull comprises two prominent ...
form the Tiki Formation that he also assigned to ''Parasuchus hislopi''. Two complete and articulated skeleton
A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...
s that include complete skulls were collected from the Lower Maleri Formation in the vicinity of the Mutapyram village of Adilabad district. Both individuals were roughly in length, lying side by side. The left individual, ISI R 42, is perfectly preserved, and was designated as the neotype
In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to anchor or centralizes ...
of the species. The right individual, ISI R 43, is nearly complete and only missing part of the snout.
Two articulated and almost complete skeleton
A skeleton is the structural frame that supports the body of most animals. There are several types of skeletons, including the exoskeleton, which is a rigid outer shell that holds up an organism's shape; the endoskeleton, a rigid internal fra ...
s of '' Malerisaurus robinsonae'' (both designated as ISIR 150), an azendohsaurid archosauromorph, were found as presumable gastric contents of these two skeletons. From the same locality as the neotype, three isolated conjoined basioccipital/basisphenoids (ISI R 45-47) were also recovered. A couple of miles north of that locality, near the Venkatapur village, two more excellently preserved skulls were found. ISI R 160 represents an isolated but nearly complete skull, while ISI R 161 represents partial skull and articulated postcranial remains. Finally, a skull recovered from the '' Tikisuchus'' holotype site of the Tiki Formation ( Gondwana Group), about 4 miles west of Tiki village of Shadol District, Madhya Pradesh, is missing only the end of the snout and the squamosal. As the lectotype of the genus, it was found nearby '' Paradapedon'' remains. Both formations date to the late Carnian
The Carnian (less commonly, Karnian) is the lowermost stage (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227.3 ...
to early Norian
The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...
stage of the Late Triassic
The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch a ...
period, about 222.5-212 million years ago
Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds.
Usage
Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...
.
Classification
The two articulated skeletons, ISI R 42-43, alone represent the most complete phytosaurs known to date. Additionally, ''Parasuchus'' has been found as one of the most primitive phytosaurs in phylogenetic analyses of Phytosauria, making it very significant for understanding the origin of the Phytosauria. Some studies, like Chatterjee (1978) and Lucas ''et al.'' (2007), synonymized ''Parasuchus'' with another basal phytosaur, '' Paleorhinus''. If this is the case, the name ''Parasuchus'' would have precedence over ''Paleorhinus'' because ''Paleorhinus'' was named in 1904, nineteen years after ''Parasuchus'' was named. A phylogenetic analysis conducted by Kammerer ''et al.'' (2016) confirmed that ''Parasuchus hislopi'' is nested within the least inclusive clade containing the species ''Paleorhinus bransoni'' and ''Paleorhinus angustifrons''. The authors thus considered the genus ''Parasuchus'' to be a senior synonym of the genus ''Paleorhinus'' (as well as '' Arganarhinus''), and referred the species ''Paleorhinus bransoni'', ''Paleorhinus angustifrons'' and ''Arganarhinus magnoculus'' to the genus ''Parasuchus''. The cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
below follows Kammerer ''et al.'' (2016).
Etymology
''Parasuchus'' was first described and named by Richard Lydekker
Richard Lydekker (; 25 July 1849 – 16 April 1915) was a British naturalist, geologist and writer of numerous books on natural history. He was known for his contributions to zoology, paleontology, and biogeography. He worked extensively in cata ...
in 1885 and the type species
In International_Code_of_Zoological_Nomenclature, 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 spe ...
is ''Parasuchus hislopi''. The generic name is derived from the Greek
Greek may refer to:
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 of all kno ...
''para''/παρα meaning "beside" or "near" and ''suchus'' from the Greek ''souchos'', which refers to the Egyptian crocodile-headed god Sobek
Sobek (), also known as Suchus (), was an ancient Egyptian deities, ancient Egyptian deity with a complex and elastic history and nature. He is associated with the Nile crocodile and is often represented as a crocodile-headed humanoid, if not a ...
. The specific name, ''hislopi'', honors Hislop who drawn attention in 1854 to the red clays near Maleri village in which the holotype (and later the neotype and other specimens) of ''P. hislopi'' was recovered.
References
{{Taxonbar, from=Q251814
Phytosauria
Prehistoric reptile genera
Late Triassic reptiles of Asia
Triassic India
Fossils of India
Taxa named by Richard Lydekker
Fossil taxa described in 1885