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A new look at ichthyosaur long bone microanatomy and histology: Implications for their adaptation to an aquatic life
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RBINS Staff Publications
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A new Lower Cretaceous ichthyosaur from Russia reveals skull shape conservatism within Ophthalmosaurinae
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Ophthalmosaurinae is a recently recognized clade of derived ichthyosaurs (marine reptiles) ranging from the Bajocian (Middle Jurassic) to the late Albian (late Early Cretaceous). Whereas the Middle–Late Jurassic ophthalmosaurine Ophthalmosaurus is often regarded as a hyperspecialized deep diver, very little is known about the anatomy, evolutionary history and ecology of Cretaceous ophthalmosaurines because of the scarcity of the fossils and the lack of well-preserved skull material. Here, we describe the skull of a new basal ophthalmosaurine ichthyosaur, Leninia stellans gen. et sp. nov., from the lower Aptian of western Russia, and compare the ocular characteristics of ophthalmosaurids. Leninia is recovered as a basal ophthalmosaurine; it possesses unique traits such as a star-shaped frontal–parietal suture as well as features previously thought to be unique to Ophthalmosaurus such as a supratemporal–stapes contact. A large sclerotic aperture – significantly larger than in platypterygiine ophthalmosaurids and similar to that of the largest-eyed modern animals (giant and colossal squids) – and reduced dentition appear widespread within ophthalmosaurines. This conservatism suggests ophthalmosaurine ophthalmosaurids occupied similar ecological niche(s) throughout their long evolutionary history.
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A New Mammal Skull from the Late Cretaceous of Romania and Phylogenetic Affinities of Kogaionid Multituberculates
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Among the Late Cretaceous fossil sites of Europe, only those from the so-called “Haţeg Island” in Transylvania, western Romania, are remarkable by their abundance in mammal remains. Curiously, all of them belong to a single family of multituberculates, the Kogaionidae, one of the rare families that survived the Cretaceous-Paleogene mass extinction in Europe. Kogaionids are mostly represented by isolated teeth except for three partial large skulls from the Maastrichtian Sânpetru Formation of the Haţeg Basin that have been described from the Sânpetru locality as Kogaionon ungureanui and from the Pui locality as Barbatodon transylvanicus and Litovoi tholocephalos. Here we report for the first time the discovery of a partial skull associated with p4 of a small-sized kogaionid from the Nălaţ-Vad locality in the Sânpetru Formation that we refer to Kogaionon radulescui, sp. nov. An updated phylogenetic analysis, including seven Maastrichtian and Paleocene kogaionids is performed and confirms that Kogaionidae is a monophyletic clade at the base of Cimolodonta. Kogaionon differs from Barbatodon in its narrower snout, proportionally smaller P1, narrower anterior part of P4 with four similar-sized cusps in the middle row, more squared or rounded M1 with an anteroposteriorly longer lingual row, and shorter p4 (at least for K. radulescui). Litovoi tholocephalos is here considered to be a junior synonym of B. transylvanicus. Despite their Maastrichtian age, the very simple and conservative dental morphology of these Romanian kogaionids suggests that they originated from an eobaatarid-like ancestor dispersing from Asia or possibly already existing in Europe between the Barremian and Albian, 40 to 55 Ma earlier.
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RBINS Staff Publications 2021
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A new Miocene baleen whale from the Peruvian desert
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RBINS Staff Publications 2016
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A new Miocene baleen whale from Peru deciphers the dawn of cetotheriids
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RBINS Staff Publications 2017
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A new monachine seal (Monachinae, Phocidae, Mammalia) from the Miocene of Cerro La Bruja (Ica department, Peru)
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RBINS Staff Publications 2023
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A new odontocete (toothed cetacean) from the Early Miocene of Peru expands the morphological disparity of extinct heterodont dolphins
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RBINS Staff Publications 2017
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A new Oligocene site with terrestrial mammals and a selachian fauna from Minqar Tibaghbagh, the Western Desert of Egypt
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A new fossil site at Minqar Tibaghbagh, east of Siwa, in the Egyptian Western Desert is described. This represents the first place in Egypt outside the Fayum Depression yielding Paleogene, terrestrial mammals. Initial studies indicate the presence of palaeomastodonts, hyracoids, and anthracotheres, presumably early Oligocene in age. As only surface prospecting has been performed, more taxa will almost certainly be discovered in future investigations here and probably also elsewhere in the surroundings. A comparison is made with the most important contemporaneous sites in Libya and Egypt that yield terrestrial mammal remains. The selachian fauna from a higher level in the section confirms the Paleogene age of the subjacent strata. It is compared with selachians faunas from the early Oligocene Eastern Tethys Ocean at other places (the Fayum Depression in Egypt, and sites in Oman and Pakistan), and differs from these sites in being fully marine. Contrary to earlier studies, the open marine mudstones of the Daba’a Formation at Minqar Tibaghbagh are overlain by Paleogene marine sediments of most probably early Oligocene age and not early Miocene marine sediments as previously reported. These strata represent not only a new site with great potential for future finds, but also allows for biostratigraphic correlation.
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RBINS Staff Publications 2017
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A new Palaearctic Amblypsilipus Species (Insecta, Diptera, Dolichopodidae) from Turkey
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RBINS Staff Publications
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A new palaeobatrachidé frog from the Early Paleocene of Belgium
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Palaeobatrachids are an extinct group of aquatic frogs. They occurred from the Late Cretaceous to the Pleistocene, only in Europe with the exception of one questionable species recorded in the late Maastrichtian Lance Formation of Wyoming and a second possible occurrence in the early Paleocene of Montana.Here, we describe about ninety isolated palaeobatrachid bones well-preserved in three-dimensions (maxillae, surangulars, vertebrae, urostyles, ilia and humeri) from the early Paleocene locality of Hainin (Belgium), which is the reference-level MP1-5 of the mammalian biochronological scale for the European Paleogene. These remains are clearly attributable to a single species of palaeobatrachid that presents the following typical characters: a surangular with a coronoid process bearing muscle scars on dorsal surface; a bicondylar sacro-urostylar articulation; an urostyle with a low neural crest and lacking transversal processes; a humerus with the humeral condyle in the alignment of the bone, epicondyles similar in size; an ilium presenting a large acetabular area, a short and posteriorly oriented pars ascendens, an elongate tuber superius, an horizontal depression on the inner surface of the iliac shaft and lacking the dorsal crest and the pars descendens; and procoelous vertebrae with typical crescent-like cotyle and condyle. The four known palaeobatrachid genera have all been recently synonymized with Palaeobatrachus for which at least seven species are now recognized. The taxon from Hainin differs from most Palaeobatrachus species in the absence of cubital fossa on the humerus, the presence of diapophyses on the first vertebra, and the maxilla that presents a higher number of tooth positions. It is thus referred to a new Palaeobatrachus species or a new genus depending of the definition of the genus Palaeobatrachus. Prior to this study, fragmentary remains of palaeobatrachids had been identified in the Campanian of France and Spain and in the Late Paleocene of France. The early Paleocene species from Hainin is therefore the earliest formally described species from Europe. This abstract is a contribution to the project BR/121/A3/PALEURAFRICA funded by the Belgian Science Policy Office.
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