Allodaposuchus is anextinctgenus ofcrocodyliforms that lived in what is now southern Europe during theCampanian andMaastrichtian stages, and possibly theSantonian stage, of theLate Cretaceous. Although generally classified as a non-crocodylianeusuchiancrocodylomorph, 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 fromRomania,Spain, andFrance.
Like many other Cretaceous crocodylomorphs,Allodaposuchus has a relatively small body size compared to living crocodylians. The largest known specimen ofAllodaposuchus belongs to an individual that was probably around 3 metres (9.8 ft) long.[2] Although the shape varies between species, in generalAllodaposuchus has a short, flattened, and rounded skull.Allodaposuchus precedens has a brevirostrine or "short-snouted" skull with a snout about the same length as theskull table (the region of the skull behind the eye sockets) andA. subjuniperus has a mesorostrine or "middle-snouted" skull with a snout that is longer than the skull table.[2][3] The main feature that distinguishesAllodaposuchus species from other related crocodylomorphs is the orientation of a groove at the back of the skull called the cranioquadrate passage; unlike the cranioquadrate passages of other crocodylomorphs, which are only visible at the back of the skull, the cranioquadrate passage ofAllodaposuchus is visible when the skull is viewed from the side.[4]
At least one species ofAllodaposuchus,A. hulki, may have adaptations that would have allowed it to live on land for extended periods of time.A. hulki has largesinuses in its skull that are not seen in any other crocodylian living or extinct and may have aided it in hearing out of water, as well as lightening the skull. Moreover,A. hulki has well-developed muscle attachments on itsscapula,humerus, andulna bones that would have allowed the forelimbs to have been held in a semi-erect stance suitable for walking over land. Remains ofA. hulki come from interbeddedsandstones andmarls that, based on the presence ofcharophyte algae, likely formed in ephemeralponds in a largefloodplain far from permanent bodies of water like lakes or rivers.A. hulki may therefore have spent much of its time out of water, travelling between these ponds for food.[5]
While there are severaldescribed species ofAllodaposuchus, the precise membership of the group is currently disputed.
Thetype species ofAllodaposuchus,A. precedens, was named by Hungarian paleontologistFranz Nopcsa in 1928 fromVălioara, Romania.[6] Nopcsa found bone fragments in a deposit of theHațeg Basin that dates back to the lateMaastrichtian stage – the very end of theLate Cretaceous. Several partial skulls from Spain and France were attributed toA. precedens in 2001.[7] Some of these skulls came fromCampanian-age deposits slightly older than those in Romania, meaning that the species must have persisted for about 5 million years.[2]
A 2013 study proposed that the French and Spanish fossils assigned toA. precedens in 2001 might actually represent a new unnamed species ofAllodaposuchus currently identified asAllodaposuchus sp.[2] A study published in 2005 had suggested that these fossils belong to several different genera of crocodylomorphs and that the original Romanian material is too fragmentary to assign to its own genus, makingAllodaposuchus anomen dubium or "dubious name".[8] However, the 2013 study reaffirmed the Romanian material's distinctiveness from other European Cretaceous crocodylomorphs and therefore reaffirmed the validity ofAllodaposuchus as a genus.[2] A petition to designate the specimen PSMUBB V 438 as theneotype to replace the original non-diagnostic type specimen was submitted to theInternational Commission on Zoological Nomenclature (ICZN) in 2017,[9] which was approved in 2020.[10]
In 2013, a second species ofAllodaposuchus,A. subjuniperus, was named on the basis of a skull from the late-MaastrichtianConquès Formation, part of theTremp Group, in theprovince of Huesca, Spain. The skull was found underneath ajuniper tree whose roots had grown between the bones, hence the species namesubjuniperus or "under juniper" inLatin.[2] However, in 2016,A. subjuniperus was moved to a new genus,Agaresuchus along with the type species of that genus,A. fontisensis, on the grounds that the Spanish species were sufficiently distinct fromA. precedens.[11] In 2021, a phylogenetic analysis by Blanco disputed this result, suggesting that bothA. fontisensis andA. subjuniperus belong within the genusAllodaposuchus proper, alongside the two species ofLohuecosuchus:L. megadontos andL. mechinorum.[12]
In 2014,A. palustris was described from a partial skull and other skeletal fragments found in Maastrichtian age sediments of theTremp Formation in a fossil locality called Fumanya Sud in the southernPyrenees.[13] These remains allowed for the first detailed description of thepostcranial (non-skull) anatomy ofAllodaposuchus.
A fourth species ofAllodaposuchus,A. hulki, was named in 2015 and also came from the Tremp Formation, although this time in a locality called Casa Fabà. The species is named after theHulk fromMarvel Comics, in reference to features on the bones that suggest it had strong muscles.[5]
A. palustris was described by Blanco in 2021 based on fossils discovered inLate Campanian-agedfluvial deposits inVelaux-La Bastide Neuve, inBouches-du-RhôneDepartment ofsouthern France.[12] Thespecies name is in reference to theIbero-Armorican island of theCretaceous European Archipelago.[12]
In 2016, the new genus and speciesAgaresuchus fontisensis was discovered anddescribed. It was named from theLo Hueco fossil site inFuentes,Cuenca, Spain;fontis is the Latin name of Fuentes.[11]A. subjuniperus was then also placed into the newgenusAgaresuchus.[11] However, Blanco's 2021 study has called this into question, and instead proposed that they should both be considered members ofAllodaposuchus, withAgaresuchus as a junior synonym.[12]
The genusLohuecosuchus was named in 2015 and contained two species,L. megadontos andL. mechinorum, from Spain and southern France.[14] However, Blanco's 2021 study has called this into question, and instead proposed that they should both be considered members ofAllodaposuchus, withLohuecosuchus as a junior synonym.[12]
Allodaposuchus belongs to thecladeAllodaposuchidae. The exact placement of Allodaposuchidae is still in dispute. Narváezet al. considered it thesister group toHylaeochampsidae, which together form aclade that is sister toCrocodylia.[14] Other studies have alternatively recovered them not as sister taxon, but rather as anevolutionary grade towards Crocodylia, with Hylaeochampsidae morebasal than Allodaposuchidae.[15][16] Alternatively, a 2021 analysis incorporatingpostcranial information recovered Allodaposuchidae within Crocodylia.[17]
Cladogram 1: Narváezet al., 2015 | Cladogram 2: Rio & Mannion, 2021 | Cladogram 3: Blanco, 2021
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The internalphylogeny ofAllodaposuchidae can be shown in thecladogram below from the 2021 Blanco study:[17]
| Allodaposuchidae |
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In the 2021 study, Blanco recoveredAllodaposuchus asparaphyletic, withAgaresuchus andLohuecosuchus. Accordingly, Blanco proposed thatAgaresuchus andLohuecosuchus should be consideredjunior synonyms ofAllodaposuchus.[17]
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