Penghusuchus

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Penghusuchus
Temporal range: Late Miocene, 11.5–5.3  Ma [1]
Penghusuchus pani.jpg
Skull
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Gavialidae
Genus: Penghusuchus
Shan et al., 2009
Type species
Penghusuchus pani
Shan et al., 2009

Penghusuchus is an extinct genus of gavialid crocodylian. It is known from a skeleton found in Middle to Upper Miocene rocks of Penghu Island, off Taiwan. The taxon was described in 2009 by Shan and colleagues; the type species is P. pani. [2] It may be related to two other fossil Asian gavialids: Toyotamaphimeia machikanensis of Japan and Hanyusuchus sinensis of South China. [3] It was a medium-sized gavialid with an estimated total length of 4.5 metres (15 ft). [4]

Contents

Discovery

On 25 March 2006, on the coast of Neian, Shiyu, Penghu Islands, an excavator driver Mr. Ming-Kuo Pan found a fossilized crocodylian tooth exposed in the sandstone interlayer between basaltic rocks and then dug up a whole skeleton. The skeleton is 70% complete and was found in the Yuwentao Formation of the middle Miocene (more than 10 million years ago), and its sedimentary rocks were dated as 17-15 million years ago, according to the pollen dating in the stratum, making it one of the oldest and most complete vertebrate fossils known in Taiwan. The genus name is derived from its discovery site in Penghu, and the species name honored its discoverer, Mr. Ming-Kuo Pan. It is now considered to represent a unique and extinct gavialid clade in East Asia, along with the Pleistocene Toyotamaphimeia from Japan and Taiwan and the Holocene Hanyusuchus from South China. [3] [5] [6] [7] [8]

Morphological Description

Penghusuchus has several diagnostic characters, including: anterior process of jugal, prefrontal and lacrimal is extending as the same level; anterior process of frontal truncated and attach with nasals in W-shaped; choana is triangular with a sharp anterior angle, and its lateral borders and floor of nasopharyngeal duct form Y-shaped ridge-like prominence on ventral surface of pterygoid; presence of five maxillary teeth within the range of the suborbital fenestra; 7th maxillary tooth is the largest in the first wave of maxillary teeth and maxilla is bulges; angular with a mid-dorsal process excluding surangular from posterodorsal border of external mandibular fenestra. Among these characters, the largest 7th maxillary tooth is only present on Pleistocene Toyotamaphimeia from Japan and Taiwan and the Holocene Hanyusuchus from South China, suggest a unique shared-featured of these three East-Asian taxa. Still, the size of Penghusuchus (4.5–5 m) is estimated smaller than Hanyusuchus and the Toyotamaphimeia (may over 6 m), as well as some of the characters is differ from the latter two. [3] [5] [6] [7] [8]

Although been long classified as Tomistominae, a 2019 study noted that Penghusuchus and Toyotamaphimeia both have gavialine features, with the Penghusuchus present the following features: axial diapophysis is present on axial neural arch; paired, bifurcated hypapophysis on the ventral side of vertebrae centrum; iliac blade has a prominent anterior process; development of deltopectoral crest in the humerus is weak; midline dorsal or pelvic osteoderms is rectangular and wider than long; thick basioccipital tubera with participating of the robust exoccipital ventral process; the cranio-quadrate passage on the occipital surface is obscured by the convex process of the exoccipital; the splenial symphysis of the mandible extends to the length of about 5-7 teeth and forms a broad or narrow V in dorsal view. These characters are usually observed in gavialid, suggesting that these two East Asian taxa share mosaic features of both tomistomine and gavialid, filling the evolutionary gap of the two longeirostrine crocodylians. [8]

Based the vertebrae length, the total length of Penghusuchus is estimated as 4.5 metres. The holotype of Penghusuchus is an osteological mature individual and reached sexual maturity based on its neurocentral suture in precaudal vertebrae is closed. [4]

Phylogeny

Below is a cladogram based morphological studies comparing skeletal features that shows Penghusuchus as a member of Tomistominae, related to the false gharial: [9]

Crocodylidae

Crocodylinae

Tomistominae

Xaymacachampsa

Megadontosuchus

Kentisuchus

Maroccosuchus

Dollosuchoides

Thecachampsa

Penghusuchus

Toyotamaphimeia

Tomistoma cairense

Maomingosuchus

Tomistoma schlegelii False gharial

Gavialosuchus

Tomistoma lusitanicum

Paratomistoma

Tomistoma coppensi

Based on morphological studies of extinct taxa, the tomistomines (including the living false gharial) were long thought to be classified as crocodiles and not closely related to gavialoids. [10] However, recent molecular studies using DNA sequencing have consistently indicated that the false gharial (Tomistoma) (and by inference other related extinct forms in Tomistominae) actually belong to Gavialoidea (and Gavialidae). [11] [12] [13] [14] [15] [16] [17]

Below is a cladogram from a 2018 tip dating study by Lee & Yates simultaneously using morphological, molecular (DNA sequencing), and stratigraphic (fossil age) data that shows Penghusuchus as a gavialid, related to both the gharial and the false gharial: [16]

Gavialidae

Gavialis gangeticus Gharial

Gavialis bengawanicus

Gavialis browni

Gryposuchus colombianus

Ikanogavialis

Gryposuchus pachakamue

Piscogavialis

Harpacochampsa

Toyotamaphimeia

Penghusuchus

Gavialosuchus

Tomistoma lusitanicum

Tomistoma schlegelii False gharial

Iijima and his colleagues named Hanyusuchus from Holocene South China. The phylogenetic analysis Penghusuchus pani, Hanyusuchus sinensis and Toyotamaphimeia machikanensis formed a monophyletic group. [3]

Crocodyloidea

Gavialoidea

Maroccosuchus zennaroi

Megadontosuchus arduini

Dollosuchoides densmorei

Xaymacachampsa kugleri

Kentisuchus astrei

Kentisuchus spenceri

Gavialidae

Tomistoma cairense

Tomistoma coppensi

Maomingosuchus petrolica

Tomistominae

Tomistoma schlegelii, false gharial

Tomistoma lusitanicum

Gavialosuchus eggenburgensis

Melitosaurus champsoides

Tomistoma calaritanum

Tomistoma gaudense

Thecachampsa carolinensis

Thecachampsa antiqua

Gavialinae

Paratomistoma courti

Penghusuchus pani

Toyotamaphimeia machikanensis

Hanyusuchus sinensis

Eosuchus lerichei

Eosuchus minor

Ocepesuchus eoafricanus

Eothoracosaurus mississippiensis

Thoracosaurus macrorhynchus

Thoracosaurus neocesariensis

Aktiogavialis puertoricensis

Eogavialis africanum

Argochampsa krebsi

Piscogavialis jugaliperforatus

Ikanogavialis gameroi

Siquisiquesuchus venezuelensis

Dadagavialis gunai

Gryposuchus neogaeus

Gryposuchus croizati

Aktiogavialis caribesi

Gryposuchus pachakamue

Gryposuchus colombianus

Rhamphosuchus crassidens

Myanmar gavialid

Gavialis lewisi

Gavialis bengawanicus

Gavialis gangeticus, gharial

Siwalik Gavialis

Related Research Articles

<span class="mw-page-title-main">Gavialinae</span> Subfamily of gharial crocodylians

Gavialinae is a subfamily of large semiaquatic crocodilian reptiles, resembling crocodiles, but with much thinner snouts. Gavialinae is one of the two major subfamilies within the family Gavialidae - the other being the subfamily Tomistominae, which contains the false gharial and extinct relatives.

<span class="mw-page-title-main">Gavialidae</span> Family of gharial crocodylians

Gavialidae is a family of large semiaquatic crocodilians with elongated, narrow snouts. Gavialidae consists of two living species, the gharial and the false gharial, both occurring in Asia. Many extinct members are known from a broader range, including the recently extinct Hanyusuchus. Gavialids are generally regarded as lacking the jaw strength to capture the large mammalian prey favoured by crocodiles and alligators of similar size so their thin snout is best used to catch fish, however the false gharial has been found to have a generalist diet with mature adults preying upon larger vertebrates, such as ungulates.

<span class="mw-page-title-main">False gharial</span> Species of crocodilian

The false gharial, also known by the names Malayan gharial,Sunda gharial and tomistoma is a freshwater crocodilian of the family Gavialidae native to Peninsular Malaysia, Borneo, Sumatra and Java. It is listed as Vulnerable on the IUCN Red List, as the global population is estimated at around 2,500 to 10,000 mature individuals.

<i>Tomistoma</i> Genus of crocodilians

Tomistoma is a genus of gavialid crocodilians. They are noted for their long narrow snouts used to catch fish, similar to the gharial. Tomistoma contains one extant (living) member, the false gharial, as well as potentially several extinct species: T. cairense, T. lusitanicumT. coppensi, and T. dowsoni. However, these species may need to be reclassified to different genera as studies have shown them to be paraphyletic, for example: previously assigned species T. taiwanicus from Taiwan, is reclassified to the genus Toyotamaphimeia, and T. dowsoni should be excluded from Tomistoma based on phylogenetic analysis.

<i>Toyotamaphimeia</i> Extinct genus of reptiles

Toyotamaphimeia is a genus of extinct gavialid crocodylian which lived in Japan and Taiwan during the Pleistocene. A specimen recovered in 1964 at Osaka University during the construction of a new science building has been dated to around 430–380 thousand years old based on the stratum in which it was found. Toyotamaphimeia was a fairly large crocodylian measuring approximately 6.3–7.3 metres (21–24 ft) long. Two species are named, T. machikanensis from Japan and T. taiwanica from Taiwan, both originally described as members of the genus Tomistoma.

<i>Gavialosuchus</i> Extinct genus of reptiles

Gavialosuchus is an extinct genus of gavialoid crocodylian from the early Miocene of Europe. Currently only one species is recognized, as a few other species of Gavialosuchus have since been reclassified to other genera.

<span class="mw-page-title-main">Alligatoroidea</span> Superfamily of reptiles

Alligatoroidea is one of three superfamilies of crocodylians, the other two being Crocodyloidea and Gavialoidea. Alligatoroidea evolved in the Late Cretaceous period, and consists of the alligators and caimans, as well as extinct members more closely related to the alligators than the two other groups.

Dollosuchoides, colloquially known as the Crocodile of Maransart, is an extinct monospecific genus of gavialoid crocodilian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found in the Brussel Formation of Maransart, Belgium and date back to the middle Eocene.

Ikanogavialis is an extinct genus of gavialid crocodilian. Fossils have been found in the Urumaco Formation in Urumaco, Venezuela and the Solimões Formation of Brazil. The strata from which remains are found are late Miocene in age, rather than Pliocene as was once thought. A possible member of this genus survived into the Late Holocene on Muyua or Woodlark Island in Papua New Guinea.

<i>Kentisuchus</i> Extinct genus of reptiles

Kentisuchus is an extinct genus of gavialoid crocodylian, traditionally regarded as a member of the subfamily Tomistominae. Fossils have been found from England and France that date back to the early Eocene. The genus has also been recorded from Ukraine, but it unclear whether specimens from Ukraine are referable to Kentisuchus.

Maroccosuchus zennaroi is an extinct gavialoid crocodylian from the Early Eocene of Morocco, traditionally regarded as a member of the subfamily Tomistominae.

Paratomistoma is an extinct monospecific genus of gavialoid crocodylian. It is based on the holotype specimen CGM 42188, a partial posterior skull and lower jaw discovered at Wadi Hitan, Egypt, in Middle Eocene-age rocks of the Gehannam Formation. The skull is unfused but considered morphologically mature. Paratomistoma was named in 2000 by Christopher Brochu and Philip Gingerich; the type species is P. courti in honor of Nicholas Court, who found CGM 42188. They performed a phylogenetic analysis and found Paratomistoma to be a derived member of Tomistominae, related to the false gharial. It may have been a marine or coastal crocodilian.

<span class="mw-page-title-main">Crocodyloidea</span> Superfamily of crocodiles

Crocodyloidea is one of three superfamilies of crocodilians, the other two being Alligatoroidea and Gavialoidea, and it includes the crocodiles. Crocodyloidea may also include the extinct Mekosuchinae, native to Australasia from the Eocene to the Holocene, although this is disputed.

Gryposuchinae is an extinct subfamily of gavialid crocodylians. Gryposuchines lived mainly in the Miocene of South America. However, "Ikanogavialis" papuensis may have survived more recently, into the Late Pleistocene/Holocene. Most were long-snouted coastal forms. The group was named in 2007 and includes genera such as Gryposuchus and Aktiogavialis, although a 2018 study indicates that the group might be paraphyletic and rather an evolutionary grade towards the gharial.

<span class="mw-page-title-main">Gavialoidea</span> Superfamily of large reptiles

Gavialoidea is one of three superfamilies of crocodylians, the other two being Alligatoroidea and Crocodyloidea. Although many extinct species are known, only the gharial Gavialis gangeticus and the false gharial Tomistoma schlegelii are alive today, with Hanyusuchus having become extinct in the last few centuries.

<span class="mw-page-title-main">Tomistominae</span> Subfamily of reptiles

Tomistominae is a subfamily of crocodylians that includes one living species, the false gharial. Many more extinct species are known, extending the range of the subfamily back to the Eocene epoch. In contrast to the false gharial, which is a freshwater species that lives only in southeast Asia, extinct tomistomines had a global distribution and lived in estuaries and along coastlines.

<span class="mw-page-title-main">Brevirostres</span> Taxon of reptiles

Brevirostres is a paraphyletic group of crocodilians that included alligatoroids and crocodyloids. Brevirostres are crocodilians with small snouts, and are distinguished from the long-snouted gharials. It is defined phylogenetically as the last common ancestor of Alligator mississippiensis and Crocodylus niloticus and all of its descendants. This classification was based on morphological studies primarily focused on analyzing skeletal traits of living and extinct fossil species, and placed the gharials outside the group due to their unique skull structure, and can be shown in the simplified cladogram below:

Tomistoma cairense is an extinct species of gavialoid crocodilian from the Lutetian stage of the Eocene era. It lived in North East Africa, especially Egypt. Remains of T. cairense have been found in the Mokattam Formation, in Mokattam, Egypt. Tomistoma cairense did not have a Maxilla process within their lacrimal gland, whereas all extant (living) crocodilians do.

<i>Maomingosuchus</i> Extinct genus of reptiles

Maomingosuchus is an extinct genus of gavialoid crocodylian from Late Eocene of Southeast Asia. It was discovered in Priabonian-aged deposits of China and possibly also Thailand. The type species, originally Tomistoma petrolica, was named in 1958 and was redescribed as Maomingosuchus in 2017. A second species, Maomingosuchus acutirostris, was described in 2022 from middle-upper Eocence deposits of the Na Duong Basin in northern Vietnam. It is proposed to be a basal member of Gavialoidea, or alternatively within the family Tomistominae. It was a relatively small gavialoid with an estimated total length of 3–3.5 metres (9.8–11.5 ft).

<span class="mw-page-title-main">Longirostres</span> Clade of crocodilians

Longirostres is a clade of crocodilians that includes the crocodiles and the gavialids, to the exclusion of the alligatoroids. Defined in 2003 by Harshman et al., Longirostres is a crown group defined phylogenetically as including the last common ancestor of Crocodylus niloticus and Gavialis gangeticus and all of its descendants.

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