Saltriovenator

On 4 August 1996, the first remains of Saltriovenator were discovered by amateur paleontologist Angelo Zanella, searching for ammonites in the Salnova marble quarry in Saltrio, northern Italy. Zanella had already been working for the Museo Civico di Storia Naturale di Milano and this institution after being informed sent out a team to investigate the find. Cristiano Dal Sasso and the volunteers of the Paleontological Group of Besano, under the direction of Giorgio Teruzzi managed to salvage a number of chalk blocks visibly containing bones. The skeleton had shortly before its discovery been blown to pieces by explosives used in the quarry to break the marble layers. Blocks that had been secured were inserted into a bath of formic acid for 1,800 hours to free the bones. The holotype, MSNM V3664, was found in a layer of the Saltrio Formation dating from the earliest early Sinemurian, 199 million years old. It consists of a fragmentary skeleton with a lower jaw. About 10% of the skeleton has been discovered, including a tooth, a right splenial, a right prearticular, a neck rib, fragments of the dorsal ribs and scapulae, a well preserved but incomplete furcula, humeri, metacarpal II, phalanx II-1, phalanx III-1, phalanx III-2, manual ungual III, a distal tarsal III, a distal tarsal IV and the proximal second to fifth metatarsals. The holotype individual likely died on the shores of an ancient beach before being washed out to sea. After death, the skeletal remains suffered from prolonged transport, during which many bones were lost and the remaining ones highly fragmented. Deposition occurred on a slope between a shallow carbonate platform and a deeper basin. Various scratches, grooves, and striations indicate that the carcass was subject to scavenging by marine invertebrates. The specimen represents a subadult individual, nearing its maximum size, of which the age has been estimated at twenty-four years. ==Description==

Because of the fragmentary nature of the remains, it was impossible to directly measure the size of the animal. The describing authors therefore compared the fossils with those of two theropods of a roughly similar volume. Comparing with the skeletal elements of MOR 693, an Allosaurus fragilis specimen, they conservatively concluded that the Saltriovenator holotype individual was at least seven to eight metres long. This would make Saltriovenator the largest known theropod living before the Aalenian stage, 25% longer than Ceratosaurus from the late Jurassic. Comparing with Ceratosaurus itself, resulted in a body length of 730 centimetres, a hip height of 220 centimetres and a skull length of eighty centimetres. The thighbone length would then have been about eighty to eighty-seven centimetres, which indicates a body weight of 1160 to 1524 kilogrammes. Another method consisted in extrapolating from the known length of the forelimb. Applying the usual limb ratio indicated a hindlimb length of 198 centimetres. The thighbone would then have been 822 to 887 millimetres long, indicating a weight of 1269 to 1622 kilogrammes. ==Classification==

The precise systematic position of Saltriovenator has been traditionally uncertain, but it is known to be a theropod. Dal Sasso originally referred it to the Tetanurae He later considered that it may represent an allosauroid, although in either case it would predate other members of the clades by roughly 20-30 million years. Benson considered it a member of Coelophysoidea in his review of Magnosaurus. The presence of a wishbone The 2018 description paper ran a large phylogenetic analysis, and found it to be a basal ceratosaur, the sister-taxon of Berberosaurus. The phylogenetic analysis is as shown: }} == Paleoenvironment ==

Saltriovenator was found on an open marine environment, where it was probably washed from the nearest mainland, being scavenged by invertebrates as proven by the presence of Sedilichnus sp. on the bones. Structural highs such as Monte Campo dei Fiori, the Varese-Arbostora swell, and Monte Nudo defined the basin architecture, producing shallow carbonate platforms, emergent land, and subsiding depocenters. Nearby emerged areas are known at Briançonnais with the bauxite rich “Siderolitico” linked to long emersion phase (Ladinian-Bathonian) and Western Tauern with graphitic schists and quartzites & sandy marble, overall pointing to the Lombardian sector acting as a possible land bridge with Laurasia, connected with the Calcari Grigi di Noriglio Formation in the Trento carbonate Platform, based on Theropod tracks of similar size to Saltriovenator. The main inner land was the Malossa-Zandobbio palaeohigh system in the Po Plain, tied with the Saltrio area by a regional belt of positive blocks. This Highs, if assumed as a single unit probably got 1,000-3,000 km² of intermittently exposed terrain. Indicators of subaerial conditions are seen at Castello Cabiaglio-Orino, thick "terra rossa" paleosols developed directly above the Rhaetian Zu Limestone, showing rhizoliths, alveolar structures, and meteoric diagenesis. These emerged lands bordered a gulf-shaped embayment, open northward, where shallow-marine carbonate platforms alternated with rapidly subsiding basins. Towards the Early Sinemurian the Arbostora swell submerged into a shallow open sea (ramp-slope), still bordered south and southwest by emerged land supported by terrigenous sands from eroded igneous/metamorphic rocks and terrestrial plants in the limestones. This theropod was probably the largest predator on the region. == See also ==