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A pycnodont premaxilla bearing a large incisiform tooth with an unusual crown morphology is described from the Palaeocene (Thanetian) phosphate deposits of Morocco. This peculiar tooth shows a broad, fan-shaped multicuspid crown with nine cusps, well adapted for benthic macroalgal scraping. This morph, assigned to a new species of Pycnodus (P. multicuspidatus sp. nov.), emphasizes the phenotypic plasticity of the group and documents an additional trophic specialization among Palaeogene pycnodontiform fishes. In the post-K/Pg boundary marine ecosystem of the Ouled Abdoun Basin, P. multicuspidatus sp. nov. may have opportunistically replaced Maastrichtian fish taxa with a similar front dentition and feeding behaviour, such as the putative specialized pycnodontiforms Stephanodus and Hadrodus.
Remains of a coelacanth specimen are described from Rhaetian deposits of the Var Department, southeastern France. They comprise the lower part of a branchial apparatus associated with a left lower jaw and a basisphenoid. Osteological features of the angular and basisphenoid and the teeth ornamentation allow the inclusion of the specimen in the mawsoniid family, genus and species indeterminate. Mawsoniids are known in freshwater environments from the Triassic of North America and from the Cretaceous of Western Gondwana and Europe, as well as from Late Jurassic marine environments from Europe. The new discovery here reported represents the first coelacanth from the marine Triassic of France and improves the understanding of the palaeobiogeography of the Mawsoniidae.
The plesiosaur specimen NHMUK 36184 from the Lower Jurassic of Whitby, Yorkshire and kept in the Natural History Museum of London, comprises an almost entire skeleton with nearly complete skull. It was described as one of two syntypes of Plesiosaurus homalospondylus by Owen, and selected as the lectotype by Lydekker. Extensive preparation of the skull has revealed it as one of the most complete and best-preserved Jurassic plesiosaurian skulls known, and its description adds much-needed data to our knowledge of the cranial osteology of the Plesiosauria. The three-dimensional preservation permits a relatively reliable reconstruction of its form. Microcleidus homalospondylus displays an interesting combination of cranial characters present in Jurassic plesiosauroids and Cretaceous Elasmosauridea. Its snout presents a very distinctive sculpture; the first pair of premaxillae teeth are extremely reduced; the frontal is partially overlain by the premaxillae, contacts the pineal foramen but does not contact the temporal fenestra; the jugal does not contact the orbit nor the temporal fenestra; the squamosal contacts the postorbital but not the maxilla and presents a bulb; the postfrontal contacts the posterolateral orbit margin; the anterior interpterygoid vacuity is absent; the pterygoids meet posterior to the posterior interpterygoid vacuities and are pierced by a foramen at this level; the quadrate ramus of the pterygoid presents a ventromedial flange; the parasphenoid is crested; the epipterygoid contacts the parietal; the paroccipital process is spatulate distally; the prootic presents an anteroventral process; the mandibular symphysis is keeled and bears four pairs of teeth. Microcleidus appears very similar to Hydrorion and Occitanosaurus, and the three taxa share a great number of plesiomorphic characters with basal plesiosaurians and pliosauroids.
During the Early–Late Cretaceous transition, marine ecosystems in Eurasia hosted a diverse set of large predatory reptiles that occupied various niches. However, most of our current knowledge of these animals is restricted to a small number of bonebed-like deposits. Little is known of the geographical and temporal extent of such associations. The middle Albian – middle Cenomanian phosphorite-bearing succession exposed at Annopol, Poland produces numerous ichthyosaurian and plesiosaurian fossils. These are mostly isolated skeletal elements (e.g. teeth, vertebrae), but disarticulated partial skeletons and an articulated, subvertically embedded ichthyosaur skull are also available. The following taxa are identified: ‘Platypterygius’ sp., cf. Ophthalmosaurinae, Ichthyosauria indet., Polyptychodon interruptus, Pliosauridae indet., Elasmosauridae indet. and Plesiosauria indet. The large-sized ichthyosaur ‘Platypterygius’ and the pliosaurid Polyptychodon interruptus predominate within the upper Albian – middle Cenomanian deposits. The Annopol record, combined with data from England, France and western Russia, suggests that ‘Platypterygius’ and Polyptychodon interruptus formed a long-term, stable ecological sympatry in marine ecosystems of the European archipelago, at least during the Albian – middle Cenomanian. In addition, the marine reptile assemblage from Annopol is distinct from other Eurasian ecosystems in containing also elasmosaurids in its Albian portion.
The real nature of marine reptile fossils found in England between the 1700s and the beginning of the 1900s remained enigmatic until Mary Anning's incredible fossil discoveries and their subsequent study by eminent English and French scientists. In 1820, Georges Cuvier acquired several ichthyosaur specimens found by Mary Anning, now kept or displayed in the Palaeontology Gallery of the Muséum National d'Histoire Naturelle (MNHN) in Paris. Four years later, Cuvier obtained a plesiosaur specimen from Mary Anning, only the second ever discovered. Cuvier was fascinated by these fossils and their study allowed him to apply his comparative anatomical method and to support his catastrophist theory. We have re-examined these important specimens from a historical point of view, and describe them here taxonomically for the first time since Cuvier's works. The Paris specimens belong to two different ichthyosaur genera (Ichthyosaurus and Leptonectes) and one plesiosaur genus (Plesiosaurus).
The discovery of new specimens of Pachyvaranus crassispondylus Arambourg, 1952 from the Maastrichtian phosphates of Morocco and Syria enables us to (1) redescribe in detail this poorly known varanoid lizard, (2) provide a more detailed diagnosis and (3) re-evaluate the systematic affinities of this taxon within squamates. The latter is placed in Pachyvaranidae nov., considered a new unranked clade of non-pythonomorph Varanoidea. The intense pachyosteosclerosis observed in the vertebrae and ribs suggests a primarily aquatic mode of life for Pachyvaranus. This is in accordance with the sedimentological context (shallow marine environment). As for its palaeobiogeographical distribution, Pachyvaranus is a component of the marine reptile assemblages from the southern margin of the Mediterranean Tethys, around palaeolatitudes 20° N. The osteoderms previously referred to this taxon by Arambourg are reanalysed and assigned to a teleost fish.
A new albulid fish, Phosphonatator oxyrhynchus, based on a single large neurocranium, is
described from the deposits of the Ouled Abdoun phosphatic basin, Morocco. The matrix of the fossil
contains an elasmobranch assemblage indicating a Danian age (with some redeposited Maastrichtian
elements). P. oxyrhynchus is characterized notably by its elongated snout and by a reduced patch of
teeth on the parasphenoid. Up to now, fossil fishes from the Ouled Abdoun phosphatic basin were
mainly known by isolated remains, and the recovery of this specimen should be ranked equal to the
recent discovery of important, very well-preserved new material of vertebrates in the Sidi Daoui area.
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