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Aigialosuchus Temporal range: Early Campanian | |
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Teeth attributed to Aigialosuchus sp. found in the Kristianstad Basin | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauria |
Clade: | Pseudosuchia |
Clade: | Crocodylomorpha |
Clade: | Crocodyliformes |
Family: | † Dyrosauridae |
Genus: | † Aigialosuchus Persson, 1959 |
Species: | †A. villandensis |
Binomial name | |
†Aigialosuchus villandensis Persson, 1959 | |
Aigialosuchus is an extinct genus of long-snouted crocodylomorph that lived in what is now Sweden during the Campanian stage of the Late Cretaceous period. The name Aigialosuchus comes from the Greek αἰγιαλός (aigialos), meaning "seashore", and σοῦχος (souchus), meaning "crocodile". The genus contains a single species, A. villandensis, described in 1959 by Per Ove Persson based on material recovered from the Kristianstad Basin in southern Sweden.
The known fossil material of Aigialosuchus consists of a partial skull and isolated teeth from southern Sweden, with possible additional teeth found on Zealand in Denmark. The fragmentary nature of these remains means that the precise classification of the genus remains uncertain. Though typically classified as an eusuchian, since 2016 it has been repeatedly placed within the more basal family Dyrosauridae.
In the Cretaceous, southern Scandinavia was covered by shallow sea and the Ivö Klack site within the Kristianstad Basin, where most of the fossils referred to Aigialosuchus have been found, was a small and rocky island. Many other dyrosaurids were marine, a lifestyle possibly shared by Aigialosuchus since its fossils have been discovered in marine deposits. Its teeth were short and stout, possibly an adaptation towards feeding on large fish and invertebrates.
Aigialosuchus was described by Swedish paleontologist Per-Ove Persson in 1959 based on fossil material recovered at the Ivö Klack locality in the Kristianstad Basin. The generic name derives from the Greek αἰγιαλός (aigialos), meaning "seashore", and σοῦχος (souchus), meaning "crocodile". [1] The species name of the only species referred to the genus, A. villandensis, derives from the Villand district of Skåne, where the fossils were found. The material Persson based Aigialosuchus on were the remains of the anterior part of the skull and of the mandibles, including some detached teeth, belonging to a single individual. Persson considered this material to be enough to clearly differentiate the fossil animal from all other known long-snouted crocodylomorphs, noting that the main distinguishing feature was the nasal bone of Aigialosuchus extending to the fenestra exonarina communis (a fusion of the fenestrae exonarinae, or bony nostrils, of both sides of the skull). [2]
In 2017, Greenlandic paleontologist Jan S. Adolfssen, Danish paleontologist Jesper Milàn and American paleontologist Matt Friedman noted that a single, rather blunt and wide crocodylomorph tooth from the Faxe quarry in the Middle Danian-aged Faxe Formation at Faxe, Denmark, might be referrable to either Aigialosuchus or to some genus within the Alligatoroidea. [3] A similar tooth also discovered in Early to Middle Paleocene deposits, this time at Gemmas Allé in Copenhagen, in 2014, also accorded well with Persson's description of Aigialosuchus teeth, though it was not referred to the genus due to the lack of a formal comparison to the type material. [4]
Aigialosaurus was a long- and narrow-snouted crocodylomorph. [1] [5] [6] The bony nostrils on both sides of the head were fused to form a single larger fenestra (skull opening), dubbed by Persson as a fenestra exonarina communis. The nasal bones on both sides of the skull extended forwards until reaching the margin of this skull opening, this being the main diagnostic feature of the genus. [7] Another diagnostic feature is the mandibular symphysis (the connection between the left and right mandible) of Aigialosuchus being unusually long, [1] 13.8 centimetres (5.4 inches), [8] and being reached by the splenial bone. [1]
The foremost part of the skull of Aigialosuchus was broadened considerably and separated from the rest of the skull by paired notches on both sides, at the level of the fourth mandibular teeth, similar to the condition in many other crocodylomorphs. The widest portion of the broadened part is 7.1 centimetres (2.8 inches) wide and the width at the point of the notches is just 4.7 centimetres (1.85 inches). [2] The foremost part of the lower jaw, which is generally narrow similar to the upper jaw, was broadened as well, though not to the same extent as the snout. [8]
In contrast to modern crocodylians, which typically have long and slender teeth, the teeth of Aigialosuchus were stout and short. [5] [8] The teeth were also somewhat recurved and had cylindrical roots. The surface of the teeth was striated (covered in ridges) densely from the base to the tip. [8]
Persson classified Aigialosuchus as a true crocodile, placing it within the subfamily Crocodylinae. [1] He based this on the distinct notch in the upper jaw. Persson also noted that since Aigialosuchus is quite poorly known, detailed comparisons with other crocodylines were impossible. [2]
Persson's classification of Aigialosuchus as a crocodyline is no longer considered likely. In 2001, American paleontologist Christopher Brochu noted that Aigialosuchus was an enigmatic crocodyliform, but probably a eusuchian (the group that contains all living crocodilians). [9] Because of the fragmentary material, Aigialosuchus was considered a problematic taxon by French paleontologist Jeremy E. Martin and Italian paleontologist Massimo Delfino in 2010, though they noted, like Brochu, that it was likely to have been a eusuchian. Although the narrow snout of Aigialosuchus is similar to the narrow snouts within the genera in the Gavialoidea (today containing only the gharial), they considered it to be unlikely that Aigialosuchus is part of that superfamily on account of the nasal of Aigialosuchus contributing to the posterior margin of the bony nostrils. [4]
In 2014, German paleontologist Daniela Schwarz-Wings and Danish paleontologists Jesper Milàn and Palle Gravesen considered the features of Aigialosuchus to accord better with the Crocodyloidea than with the Gavialoidea, but noted that Aigialosuchus significantly predated the earliest similar crocodyloid genera. Schwarz-Wings, Milàn and Gravesen noted that until a taxonomic revision of the Aigialosuchus material is carried out, its precise systematic position within the entire Crocodylomorpha will remain unclear. [4]
In 2014, French paleontologists Jeremy E. Martin, Romain Amiot and Christophe Lécuyer and English paleontologist Michael J. Benton noted that Persson's description of Aigialosuchus accorded well with the known material of known contemporary freshwater eusuchians. [10]
In a 2016 paper by Australian paleontologist Benjamin Kear and colleagues, Aigialosuchus was considered to have been a dyrosaurid, not a eusuchian. [11] Aigialosuchus was also classified as a dyrosaurid in a 2018 paper by Swedish paleontologist Elisabeth Einarsson. [6]
Certain fossils of Aigialosuchus have only been recovered from the Campanian-age deposits in the Kristianstad Basin in Sweden. During the Campanian, the Kristianstad Basin was a subtropical to temperate shallow inland sea home to a diverse marine fauna characteristic of shallow marine life of an inner shelf community and included abundant algae, brachiopods, bryozoans, molluscs (including bivalves, gastropods, belemnites and the ammonites), sea urchins, serpulids, decapods and sponges. [12] [13] Additionally, fish (including a vast array of sharks) were also common and fossils of many species of reptiles, most of them marine, have also been found, including mosasaurs, sea turtles, crocodylomorphs and a few dinosaurs. [14]
The fossils of Aigialosuchus described by Persson in 1959 were recovered from marine sediments, though Persson noted that this was not necessarily an indicator that Aigialosuchus itself would have been purely marine. According to Persson, Aigialosuchus could also have lived in the littoral zone or in a river adjacent to the mainland. [2] Within the Kristianstad Basin, the fossil site Ivö Klack has yielded the most Aigialosuchus fossils. Ivö Klack was a small, rocky island during the Cretaceous. The presence of Aigialosuchus at the site might indicate that Aigialosuchus preferred to live in coastal waters, where it could lay its eggs on adjacent land, rest and heat up, similar to modern crocodilians. [15]
Most recent and modern long-snouted crocodylomorphs (notably the gharials) have slender and long teeth, being piscivores. The teeth of Aigialosuchus were stout and short, meaning that it would probably have been adapted to some other form of feeding. According to Einarsson, the robust teeth of Aigialosuchus indicate that it was adapted for feeding on larger fish, such as Enchodus , and larger invertebrates. Contrary to Persson's initial assessment, Aigialosuchus is now believed to have been a marine animal, similar to other dyrosaurids. [5]
Allodaposuchus is an extinct genus of crocodyliforms that lived in what is now southern Europe during the Campanian and Maastrichtian stages, and possibly the Santonian stage, of the Late Cretaceous. Although generally classified as a non-crocodylian eusuchian crocodylomorph, it is sometimes placed as one of the earliest true crocodylians. Allodaposuchus is one of the most common Late Cretaceous crocodylomorphs from Europe, with fossils known from Romania, Spain, and France.
Mahajangasuchus is an extinct genus of crocodyliform which had blunt, conical teeth. The type species, M. insignis, lived during the Late Cretaceous; its fossils have been found in the Maevarano Formation in northern Madagascar. It was a fairly large predator, measuring up to 4 metres (13 ft) long.
Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine, with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.
Arambourgisuchus is an extinct genus of dyrosaurid crocodylomorph from the late Palaeocene of Morocco, found in the region of Sidi Chenane in 2000, following collaboration by French and Moroccan institutions, and described in 2005 by a team led by palaeontologist Stéphane Jouve. Arambourgisuchus was a large animal with an elongated skull 1 meter in length.
Scanisaurus is a dubious genus of plesiosaur that lived in what is now Sweden and Russia during the Campanian stage of the Late Cretaceous period. The name Scanisaurus means "Skåne lizard", Skåne being the southernmost province of Sweden, where a majority of the fossils referred to the genus have been recovered. The genus contains one species, S. nazarowi, described in 1911 by Nikolay Bogolyubov as a species of Cimoliasaurus based on a single vertebral centrum discovered near Orenburg, Russia.
Hyposaurus is a genus of extinct marine dyrosaurid crocodyliform. Fossils have been found in Paleocene aged rocks of the Iullemmeden Basin in West Africa, Campanian–Maastrichtian Shendi Formation of Sudan and Maastrichtian through Danian strata in New Jersey, Alabama and South Carolina. Isolated teeth comparable to Hyposaurus have also been found in Thanetian strata of Virginia. It was related to Dyrosaurus. The priority of the species H. rogersii has been debated, however there is no sound basis for the recognition of more than one species from North America. The other North American species are therefore considered nomina vana.
Argochampsa is an extinct genus of eusuchian crocodylomorph, usually regarded as a gavialoid crocodilian, related to modern gharials. It lived in the Paleocene of Morocco. Described by Hua and Jouve in 2004, the type species is A. krebsi, with the species named for Bernard Krebs. Argochampsa had a long narrow snout, and appears to have been marine in habits.
Acynodon is an extinct genus of eusuchian crocodylomorph from the Late Cretaceous, with fossils found throughout Southern Europe.
Eothoracosaurus is an extinct monospecific genus of eusuchian crocodylomorphs found in Eastern United States which existed during the Late Cretaceous period. Eothoracosaurus is considered to belong to an informally named clade called the "thoracosaurs", named after the closely related Thoracosaurus. Thoracosaurs in general were traditionally thought to be related to the modern false gharial, largely because the nasal bones contact the premaxillae, but phylogenetic work starting in the 1990s instead supported affinities within gavialoid exclusive of such forms. Even more recent phylogenetic studies suggest that thoracosaurs might instead be non-crocodilian eusuchians.
Hylaeochampsa is an extinct genus of eusuchian crocodylomorphs. It is known only from a partial skull recovered from Barremian-age rocks of the Lower Cretaceous Vectis Formation of the Isle of Wight. This skull, BMNH R 177, is short and wide, with a eusuchian-like palate and inferred enlarged posterior teeth that would have been suitable for crushing. Hylaochampsa was described by Richard Owen in 1874, with H. vectiana as the type species. It may be the same genus as the slightly older Heterosuchus, inferred to have been of similar evolutionary grade, but there is no overlapping material as Heterosuchus is known only from vertebrae. If the two could be shown to be synonyms, Hylaeochampsa would have priority because it is the older name. Hylaeochampsa is the type genus of the family Hylaeochampsidae, which also includes Iharkutosuchus from the Late Cretaceous of Hungary. James Clark and Mark Norell positioned it as the sister group to Crocodylia. Hylaeochampsa is currently the oldest known unambiguous eusuchian.
Thoracosaurus is an extinct genus of long-snouted eusuchian which existed during the Late Cretaceous and Early Paleocene in North America and Europe.
Pholidosaurus is an extinct genus of neosuchian crocodylomorph. It is the type genus of the family Pholidosauridae. Fossils have been found in northwestern Germany. The genus is known to have existed during the Berriasian-Albian stages of the Early Cretaceous. Fossil material found from the Annero and Jydegård Formations in Skåne, Sweden and on the island of Bornholm, Denmark, have been referred to as a mesoeucrocodylian, and possibly represent the genus Pholidosaurus.
Phosphatosaurus is an extinct genus of dyrosaurid crocodylomorph. It existed during the early Eocene, with fossils having been found from North Africa in Tunisia and Mali. Named in 1955, Phosphatosaurus is a monotypic genus; the type species is P. gavialoides. A specimen has been discovered from Niger, but it cannot be classified at the species level.
Cerrejonisuchus is an extinct genus of dyrosaurid crocodylomorph. It is known from a complete skull and mandible from the Cerrejón Formation in northeastern Colombia, which is Paleocene in age. Specimens belonging to Cerrejonisuchus and to several other dyrosaurids have been found from the Cerrejón open-pit coal mine in La Guajira. The length of the rostrum is only 54-59% of the total length of the skull, making the snout of Cerrejonisuchus the shortest of all dyrosaurids.
Rhabdognathus is an extinct genus of dyrosaurid crocodylomorph. It is known from rocks dating to the Paleocene epoch from western Africa, and specimens dating back to the Maastrichtian era were identified in 2008. It was named by Swinton in 1930 for a lower jaw fragment from Nigeria. The type species is Rhabdognathus rarus. Stéphane Jouve subsequently assessed R. rarus as indeterminate at the species level, but not at the genus level, and thus dubious. Two skulls which were assigned to the genus Rhabdognathus but which could not be shown to be identical to R. rarus were given new species: R. aslerensis and R. keiniensis, both from Mali. The genus formerly contained the species Rhabdognathus compressus, which was reassigned to Congosaurus compressus after analysis of the lower jaw of a specimen found that it was more similar to that of the species Congosaurus bequaerti. Rhabdognathus is believed to be the closest relative to the extinct Atlantosuchus.
Arenysuchus is an extinct monospecific genus of allodaposuchid eusuchian crocodylomorph from Late Cretaceous deposits of north Spain. It is known from the holotype MPZ ELI-1, a partial skull from Elías site, and from the referred material MPZ2010/948, MPZ2010/949, MPZ2010/950 and MPZ2010/951, four teeth from Blasi 2 site. It was found by the researchers José Manuel Gasca and Ainara Badiola from the Tremp Formation, in Arén of Huesca, Spain. It was first named by Eduardo Puértolas, José I. Canudo and Penélope Cruzado-Caballero in 2011 and the type species is Arenysuchus gascabadiolorum.
Lohuecosuchus is an extinct genus of allodaposuchid eusuchian crocodylomorph that lived during the Late Cretaceous in what is now Spain and southern France.
Agaresuchus is an extinct genus of allodaposuchid eusuchian crocodylomorph from the Late Cretaceous (Campanian-Maastrichtian) of Spain. It includes two species, the type species A. fontisensis, and A. subjuniperus, which was originally named as a species of the related genus Allodaposuchus. However, it has been proposed that both species may instead belong to the genus Allodaposuchus.
The Kristianstad Basin is a Cretaceous-age structural basin and geological formation in northeastern Skåne, the southernmost province of Sweden. The basin extends from Hanöbukten, a bay in the Baltic Sea, in the east to the town of Hässleholm in the west and ends with the two horsts Linderödsåsen and Nävlingeåsen in the south. The basin's northern boundary is more diffuse and there are several outlying portions of Cretaceous-age sediments. During the Cretaceous, the region was a shallow subtropical to temperate inland sea and archipelago.
The Kristianstad Basin is a Cretaceous-age structural basin and geological formation in northeastern Skåne, the southernmost province of Sweden. The sediments in the basin preserves a wide assortment of taxa represented in its fossil record, including the only non-avian dinosaur fossils in Sweden and one of the world's most diverse mosasaur faunas.