Cricosaurus bambergensis: A new species of Metriorhynchid Crocodylomorph from the Late Jurassic of Bavaria, southern Germany.

The Metriorhynchids were Mesozoic Thalattosuchian Crocodylomorphs adapted to a fully aquatic marine lifestyle. Their limbs were modified into paddle-like flippers, they has a shark-like tail-fin and had lost the osteoderms in their skin. Meriorhynchids appear to have been fully pelagic, i.e. capable of swimming freely in ocean currents, rather than being restricted to inshore environments. The Meriorhynchids appeared in the Middle Jurassic and survived into the Early Cretaceous. The genus Cricosaurus currently contains nine species of Metriorhynchid Crocodylomorphs from the Late Jurassic and Early Cretaceous of Europe and North America, however cladistic analysis (computerised analysis of relationships within the group based entirely upon shared common features rather than assumed relationships) has suggested that two members of the genus, Cricosaurus saltillensis and Cricosaurus macrospondylus may be more closely related to other Metriorhynchids than they are to the other members of the genus.

In a paper published in the journal Acta Palaeontologica Polonica on 4 April 2019, Sven Sachs of the Naturkunde-Museum Bielefeld, Mark Young of the School of GeoSciences at the University of Edinburgh, Pascal Abel of the Senckenberg Centre for Human Evolution and Palaeoenvironment at Eberhard- Karls Universität Tübingen, and Heinrich Mallison of Palaeo3D, describe a new species of Cricosaurus from the Late Jurassic Torleite Formation of Wattendorf near Bamberg in Bavaria, southern Germany.

The late Kimmeridgian (roughly 155-152 million years old) Torleite Formation of the Franconian Jura comprises a series of Late Jurassic shallow-marine sediments, including numerous Sponge-Microbial reef structures and micritic lithographic limestones, the oldest examples of these highly fossiliferous deposits in southern Germany. The new specimen comes from the Wattendorf Member from a quarry near Bamburg, a course microtic limestone dated to the Aulacostephanus pseudomutabilis  Ammonite Zone (about 153.96 to 153.55 million years old), a deposit that has produced numerous Plants, Invertebrates Fish, Rhynchocephalians, Turtles, Pterosaurs, and Thalattosuchians, which were preserved after settling on the floor of lagoons between the reefs, where dysoxic or anoxic conditions prevailed beneath an oxidated, plankton-rich upper water column, favouring the preservation of articulated skeletons in calcareous mud.

The new species is named Cricosaurus bambergensis, meaning 'from Bamburg'. It is described from a single specimen comprising an almost complete articulated skeleton preserved with the skull in ventral view and the body in lateral view.

Metriorhynchid Thalattosuchian Cricosaurus bambergensis, late Kimmeridgian of Wattendorf (southern Germany). Skeleton in ventrolateral view. Sachs et al. (2019).

The skull of the specimen is damaged, but the mandible and palate are well preserved, with sutures clearly visible. Twenty three teeth are visible on the right maxilla, with three teeth present on the premaxila; the dentary is less well preserved and the number of teeth unclear. The teeth are slender, labiolingually compressed (i.e. longer front-to-back than side-to-side), and elliptical in cross-section. A low-keeled carina (ridge) is present on the front and back edges of the teeth.

Metriorhynchid Thalattosuchian Cricosaurus bambergensis, late Kimmeridgian of Wattendorf (southern Germany). (A) Dentition. (B) Palatines showing the midline keel seperating symmetrical depressions (dashed outline). (C) First cervical vertebrae. Abbreviations: aac, atlas-axis vertebrae; cv, cervical vertebra; hy, hyoid. Sachs et al. (2019).

The specimen has seven cervical (neck), eighteen dorsal (back), and two sacral (lower back) vertebrae, with each of the dorsal and sacral vertebrae supporting a slender, slightly offset, rib. Within the rib cage parts of a gastralium (gastral basket) can be seen. The tail comprises fifty four vertebrae, twenty eight preflexural, six flexural (the bit where the tail bends) and twenty postflexural, though there is a break after the thirteenth vertebra.

Metriorhynchid Thalattosuchian Cricosaurus bambergensis, late Kimmeridgian of Wattendorf (southern Germany). Distal part of the tail showing the flexural and postflexural region. Sachs et al. (2019).

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Redescription of a Thalattosuchian Crocodyliform from the Jurassic-Cretaceous boundary of Patagonia.

Purranisaurus potens is known from a single partial specimen from the left margin of the Arroyo del Cajón Grande in southeast Malargüe Department, Mendoza Province, in the Neuquún Basin of west-central Argentina. It was first described in 1948 as a Plesiosaur, then reclassified as a Nothosaur in 1967. Since this time it has generally been considered to be a Metriorhynchid Thalattosuchian, a sort of Mesozoic Marine Crocodyliform, and a close relationship to two Chilean species, Metriorhynchus  casamiquelai and Metriorhynchus westermanni, and it has been suggested that the three species be placed in a single genus, though these analyses have been based upon photographs and descriptions from the original papers describing the specimen, rather than re-examination of the material.

In a paper published in the Journal of Vertebrate Paleontology on 20 February 2015, Yanina Herrera, Zulma Gasparini and Marta Fernández of the División Paleontología Vertebrados at the Museo de La Plata at the Universidad Nacional de La Plata redescribe the Purranisaurus potens, following repreparation of the original specimen at the Museo de La Plata during which more of the skull was exposed from the matrix.

The single known specimen of Purranisaurus potens comprises a three-dimensionally preserved skull with damage to the orbital region (area around the eyes) caused by post-mortem compression, as well as a partial left lower jaw. The original description also included several ribs and vertebrae, however these could not be located and appear to have been lost.

Purranisaurus potens in left lateral view. (A) Photograph; (B) line interpretation. Abbreviations: eor, external otic recess; fr, frontal; gd, nasal gland duct; j, jugal; la, lacrimal; ls, laterosphenoid; mx, maxilla; na, nasal; or, orbit; pa, parietal; pfr, prefrontal; po, postorbital; pro, prootic; q, quadrate; sq, squamosal; sqs, squamosal flat surface. Scale bar equals 10 cm. Herrera et al. (2015).

Based upon the new description Herrera et al. were able to re-analyse the phylogenetic position of Purranisaurus potens. This new analysis suggests that the species belongs firmly within the Geosaurine group of Metriorhynchids, and shows no close relationship with Metriorhynchus  casamiquelai and Metriorhynchus westermanni, and the true relationships of these two species remains unclear, with Herrera et al.’s analysis suggesting they occupy a basal position within the Geosaurinae, and are not closely related to other members of the genus Metriorhynchus.

Strict consensus topology of the unordered phylogenetic analysis. Herrera et al. (2015).

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The Rosso Ammonitico Veronese Crocodylomorph. 

The Rosso Ammonitico Veronese is a red nodular limestone found on the Trento Plateau in northern Italy, and Middle to Late Jurassic in age. It is noted for its numerous Ammonite fossils, but also produces occasional Marine Reptiles, notably Thalattosuchian Crocodylomorphs and Plesiosaurians. The earliest recorded discovery of such a Reptile is a...

A Thalattosuchian Crocodiliforme from the Late Cretaceous of Argentina.

The Thalattosuchians were a group of marine Crocodiliformes (the group of Archosaurs that includes modern Crocodiles and a diverse range of Mesozoic animals) that were found in seas around the world from the Early Jurassic to the Early Cretaceous. They...

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The Rosso Ammonitico Veronese Crocodylomorph.

The Rosso Ammonitico Veronese is a red nodular limestone found on the Trento Plateau in northern Italy, and Middle to Late Jurassic in age. It is noted for its numerous Ammonite fossils, but also produces occasional Marine Reptiles, notably Thalattosuchian Crocodylomorphs and Plesiosaurians. The earliest recorded discovery of such a Reptile is a Crocodylian discovered in 1787 at a quarry on Mount Zovetto, near Tresche, in the Asiago Municipality, though the exact location of this quarry is no longer known. It is currently housed in the Museo Paleontologico dell’Universitàdi Padova.

The Crocodylomorph was named ‘Steneosaurus barettoni’ in 1883 by Achille de Zigno, though he provided no formal description of the fossil, which makes his naming of the specimen invalid under current rules on taxonomy. The first formal description of the specimen was made by Giovanni Omboni in 1890.

In a paper published in the journal Historical Biology on 4 April 2013, Andrea Cau of the Museo Geologico ‘Giovanni Capellini’ in Bologna redescribes the Rosso Ammonitico Veronese Crocodylomorph, and attempts to resolve its classification.

The Rosso Ammonitico Veronese Crocodylomorph. Photograph (A) and line drawing (B). In (B), dark grey tone indicates preserved bones, light grey tone indicates natural cast of bones on slab and asterisk indicates fragment of mandible overlapped by skull. Scale bar in cm. Cau (2013).

The specimen comprises a partial skull and associated mandible preserved in a limestone slab. The skull is poorly preserved, with most of the left side eroded away. The end of the snout is missing, but preserved as an impression on the slab which preserves some fairly good detail.

As noted before, de Zigno’s naming of the specimen as ‘Steneosaurus barettoni’ is not considered valid under current rules on taxonomy. Furthermore Cau does not find any evidence for the assignation of the specimen to the Teleosauroid genus Steneosaurus, instead referring it to the Geosaurine genus Neptunidraco. Due to the poor preservation of the specimen it is not assigned to a species.

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Teeth and osteoderms of a Sebecosuchian Crocodylomorph from the Middle Eocene of France.

The Sebecosuchians were the only group of Crocodylomorphs other than the modern Crocodyliforms to survive the end Cretaceous extinction, radiating in South America and Europe during the Palaeogene, then going extinct later in the Tertiary. A variety of South American forms have been described, and the group is reasonably well...

A blunt-snouted Dryosaurid from the Palaeocene of Columbia.

 Crocodylomorphs arose during the Triassic and diversified throughout the Mesozoic, reaching a great diversity of forms by the end of the Cretaceous. However they group were badly affected by the...

A Metriorhynchid Crocodylomorph tooth from the Late Jurassic of Chesil Beach, England.

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A Thalattosuchian Crocodiliforme from the Late Cretaceous of Argentina.

The Thalattosuchians were a group of marine Crocodiliformes (the group of Archosaurs that includes modern Crocodiles and a diverse range of Mesozoic animals) that were found in seas around the world from the Early Jurassic to the Early Cretaceous. They are not closely related to modern Crocodiles, but resembled them superficially due to their aquatic adaptations, and are often referred to as 'Marine Crocodiles'.

In a paper published in the May 2013 edition of the journal Palaeontology, Yanina Herrera, Zulma Gasparini and Marta Fernández of the División Paleontología Vertebrados at the Museo de La Plata in Argentina, describe a new species of Thalattosuchian from Late Cretaceous lithographic limestone at Los Catutos in Neuquén Province, Argentina.

The new species is placed in the genus Cricosaurus, and given the specific name lithographicus, in reference to the lithographic limestone in which it was found. The specimen comprises a complete skull with articulated lower jaws, dorsal, sacral and caudal vertebrae, pectoral girdle element, incomplete forelimb, pelvic girdle elements and an incomplete hind limb, preserved in five slabs. The Skull and mandible are on a single slab; they are somewhat crushed but essentially retain their life position. The other bones are more articulated. 

Cricosaurus lithographicus, skull and mandible. (A–B) Dorsal view; (A) photograph, (B) drawing. (C–D) Ventral view; (C) photograph, (D) drawing. (E) Snout in left lateral view. Abreviations: an, angular; ar, articular; bo, basioccipital; bsp, basisphenoid; cor, coronoid; cr. B, crest B; d, dentary; en, external nares; eo, exoccipital; fm, foramen magnum; fr, frontal; j, jugal; la, lacrimal; mx, maxilla; mef, medial eustachian foramen; na, nasal; oc, occipital condyle; pa, parietal; pl, palatine; pmx, premaxilla; po, postorbital; pref, preorbital fossa; pfr, prefrontal; pt, pterygoid; q, quadrate; r.ar, retroarticular process; san, surangular; sdg, surangular-dentary groove; so, supraoccipital; sof, suborbital fenestra; sq, squamosal; stf, supratemporal fenestra. All scale bars represent 100 mm.

See also A basal Tetanuran Dinosaur tooth from the Late Jurassic of the Czech Republic, A Pliosaur from the Jurassic Coast of Dorset, A new species of Diplodocid Dinosaur from the Late Jurassic of northern Wyoming, New species of Ginglymodian Fish from the Late Jurassic of northeast Thailand and New species of Rhamphorhynchid Pterosaur from the Late Jurassic Solnhofen Limestone.

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