Allodaposuchus

Extinct genus of reptiles

Allodaposuchus is an extinct genus of crocodyliforms 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 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.

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 long. 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. 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. 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.

While there are several described species of Allodaposuchus, the precise membership of the group is currently disputed.

The type species of Allodaposuchus, A. precedens, was named by Hungarian paleontologist Franz Nopcsa in 1928 from Vălioara, Romania. 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. 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. However, the 2013 study reaffirmed the Romanian material's distinctiveness from other European Cretaceous crocodylomorphs and therefore reaffirmed the validity of Allodaposuchus as a genus. In 2021, a phylogenetic analysis by Blanco 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.

In 2014, A. palustris was described from a partial skull and other skeletal fragments found in Maastrichtian age sediments of the Tremp Formation in a fossil locality called Fumanya Sud in the southern Pyrenees. These remains allowed for the first detailed description of the postcranial (non skull) anatomy of Allodaposuchus.