Saltriovenator zanellai: New Carnivorous Dinosaur Unveiled

Friday, December 21, 2018

Life reconstruction of Saltriovenator zanellai. Image credit: Davide Bonadonna.

A partial skeleton of a ceratosaurian theropod dinosaur unearthed over two decades ago in Italy has been recognized as belonging to a new genus and species.

The newly-identified dinosaur belongs to Ceratosauria (ceratosaurs), a group of large-bodied theropod dinosaurs.

Named Saltriovenator zanellai, it lived approximately 198 million years ago (Early Jurassic epoch).

With an estimated body length of 25 feet (7.5 m), it is the largest and most robust theropod from the Early Jurassic, pre-dating the occurrence in theropods of a body mass approaching 1,000 kg by over 25 million years.

The ancient creature is also the oldest known ceratosaur and is the first Jurassic dinosaur known from Italy.

Selected elements used in the diagnosis of Saltriovenator zanellai: right humerus in medial (A), frontal (B) and distal (C) views; (D) left scapula, medial view; (E) right scapular glenoid and coracoid, lateral view; (F) furcula, ventral view; tooth, labial (G) and apical (H) views; (I) left humerus, medial view; right second metacarpal in dorsal (J), lateral (L) and distal (N) views; first phalanx of the right second digit in dorsal (K), lateral (M) and proximal (O) views; (P–T) right third digit in proximal, dorsal and lateral views; (U) right distal tarsal IV, proximal view; third right metatarsal in proximal (V) and frontal (X) views; second right metatarsal, proximal (W) and frontal (Y) views; (Z) reconstructed skeleton showing identified elements (red). Abbreviations as in text, asterisks mark autapomorphic traits. Scale bars – 10 cm in (A)–(E), (I), and (U)–(Y); two cm in (F), and (J)–(T); one cm in (G). Image credit: G. Bindellini / C. Dal Sasso / M. Zilioli / M. Auditore.

The partial skeleton of Saltriovenator zanellai was accidentally discovered in 1996 by Angelo Zanella, fossil amateur and collaborator of the Museo di Storia Naturale di Milano, in a huge quarry located in the Alpine foothills, at the Swiss-Italian border near Saltrio, less than 50 miles (80 km) north of Milan, Varese Province, Lombardy.

Many bones of the dinosaur bear feeding marks by marine invertebrates, which represent the first case on its remains and indicate that its carcass floated in a marine basin and then sunk, remaining on the sea bottom for quite a long time before burial.

“Although fragmentary, Saltriovenator zanellai shows a mosaic of ancestral and advanced anatomical features, respectively seen in the four-fingered dilophosaurids and ceratosaurs, and the three-fingered tetanuran theropods, such as allosaurids,” said Dr. Cristiano Dal Sasso, a paleontologist at the Museo di Storia Naturale di Milano.

“Paleohistological analysis indicates that Saltriovenator zanellai was a still growing subadult individual, therefore its estimated size is all the more remarkable, in the context of the Early Jurassic epoch,” added Dr. Simone Maganuco, also from the Museo di Storia Naturale di Milano.

“The evolutionary ‘arms race’ between stockier predatory and giant herbivorous dinosaurs, involving progressively larger species, had already begun 200 million of years ago.”

“The grasping hand of Saltriovenator zanellai fills a key gap in the theropod evolutionary tree: predatory dinosaurs progressively lost the pinky and ring fingers, and acquired the three-fingered hand which is the precursor of the avian wing,” said Dr. Andrea Cau, a researcher at the Museo Geologico ‘Giovanni Capellini.’

The discovery of Saltriovenator zanellai is reported in the journal PeerJ.

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C. Dal Sasso et al. 2018. The oldest ceratosaurian (Dinosauria: Theropoda), from the Lower Jurassic of Italy, sheds light on the evolution of the three-fingered hand of birds. PeerJ 6: e5976; doi: 10.7717/peerj.5976

Source: www.sci-news.com

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