Allodaposuchus
Allodaposuchus is an extinct genus of crocodyliforms that includes four species that lived in what is now southern Europe during the Campanian and Maastrichtian stages of the Late Cretaceous. Although generally classified as a non-crocodylian 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.
Like many other Cretaceous crocodylomorphs, Allodaposuchus has a relatively small body size compared to living crocodylians. The largest known specimen of Allodaposuchus belongs to an individual that was probably around 3 metres (9.8 ft) long.[1] Although the shape varies between species, in general Allodaposuchus has a short, flattened, and rounded skull. Allodaposuchus precedens has a brevirostrine or "short-snouted" skull with a snout about the same length as the skull table (the region of the skull behind the eye sockets) and A. subjuniperus has a mesorostrine or "middle-snouted" skull with a snout that is longer than the skull table.[1][2] The main feature that distinguishes Allodaposuchus 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 of Allodaposuchus is visible when the skull is viewed from the side.[3]
At least one species of Allodaposuchus, A. hulki, may have adaptations that would have allowed it to live on land for extended periods of time. A. hulki has large sinuses 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 its scapula, humerus, and ulna bones that would have allowed the forelimbs to have been held in a semi-erect stance suitable for walking over land. Remains of A. hulki come from interbedded sandstones and marls that, based on the presence of charophyte algae, likely formed in ephemeral ponds in a large floodplain 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.[4]
There are four described species Allodaposuchus. The type species of Allodaposuchus, A. precedens, was named by Hungarian paleontologist Franz Nopcsa in 1928 from Vălioara, Romania.[5] Nopcsa found bone fragments in a deposit of the Hațeg Basin that dates back to the late Maastrichtian stage – the very end of the Late Cretaceous. Several partial skulls from Spain and France were attributed to A. precedens in 2001.[6] Some of these skulls came from Campanian-age deposits slightly older than those in Romania, meaning that the species must have persisted for about 5 million years.[1]
In 2013, a second species of Allodaposuchus, A. subjuniperus, was named on the basis of a skull from the late-Maastrichtian Conquès Formation, part of the Tremp Group, in the province of Huesca, Spain. The skull was found underneath a juniper tree whose roots had grown between the bones, hence the species name subjuniperus or "under juniper" in Latin.[1] 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 from A. precedens.[7] In 2021, a phylogenetic analysis disputed this result, suggesting that both A. fontisensis and A. subjuniperus belong within the genus Allodaposuchus proper, alongside the two species of Lohuecosuchus: L. megadontos and L. mechinorum.[8]
