Endocranial morphology of Liaoceratops yanzigouensis (Dinosauria: Ceratopsia) from Early Cretaceous Jehol Biota of Liaoning in China
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Abstract:
Liaoceratops is a small basal neoceratopsian dinosaur from the Early Cretaceous Jehol Biota of western Liaoning, China. Because its postcranial skeleton is lacking, its behaviour and palaeoecology remain poorly understood. By using computed tomography (CT), we reconstructed the cranial endocast and endosseous labyrinths of an adult individual of Liaoceratops yanzigouensis (PMoL-AD00097). Analysis and comparisons indicate that the brain, olfactory bulb and inner ear of adult Liaoceratops more closely resemble those observed in adult specimens of the basal ceratopsian Psittacosaurus than those in more derived ceratopsians. The relatively large olfactory bulb, discernible floccular lobes, and relatively long semicircular canals suggest that the adult Liaoceratops had a keen sense of smell, a well-developed sensory input for the reflexive stabilisation of gaze and posture, and a nearly horizontal head posture. Based on its relatively short cochlear ducts, adult Liaoceratops likely vocalised at and heard more efficiently to relatively high frequencies than the derived ceratopsian Pachyrhinosaurus and Triceratops. The relatively well-developed semicircular canals suggest that adult Liaoceratops was agile biped and had a similar locomoter mode with adult Psittacosaurus.Keywords:
Endocast
Postcrania
Theropoda
Sponge
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Mid-Cretaceous ammonoid assemblages are newly identified from four localities in the Aridagawa area, Wakayama, southwest Japan. They consist of Middle to Upper Albian ammonoids such as Desmoceras (Pseudouhligella) dawsoni shikokuense, Puzosia subcorbarica, Mojsisoviczia sp., Oxytropidoceras sp., Mortoniceras sp., etc., and Mantelliceras japonicum, which indicates the Lower Cenomanian stage. The Albian ammonoids were found for the first time from the Chichibu Belt of Kii Peninsula. The discovery of these ammonoids indicates a considerably wide distribution of the mid-Cretaceous deposits in the Aridagawa area, and the necessity of a large revision of the previous stratigraphic division of the Cretaceous strata in the area. The mid-Cretaceous deposits in the Aridagawa area and their abundant molluscan fossils are important for reconstruction of the mid-Cretaceous paleoenvironment and tectonics in the eastern margin of Asia.
Cenomanian
Ammonoidea
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Low latitude
High latitude
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Sequence (biology)
Section (typography)
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Abstract Pliosaurid marine reptiles played important roles in marine food chains from the Middle Jurassic to the middle Cretaceous, frequently as apex predators. The evolution of pliosaurids during the later parts of the Early Cretaceous has recently been illuminated by discoveries from Russia (Hauterivian) and Colombia (Barremian). However, knowledge of pliosaurids representing the Jurassic–Cretaceous transition (late Tithonian – Valanginian), is still largely incomplete, especially during the earliest Cretaceous. As such, the effect on pliosaurids of hypothesized faunal turnover during the Jurassic–Cretaceous boundary interval is poorly understood. We report pliosaurid teeth from the upper Volgian (Tithonian, Upper Jurassic) of the Kheta river basin (Eastern Siberia, Russia), to the Berriasian and Valanginian (Lower Cretaceous) of the Volga region (European Russia). These assemblages have yielded a series of distinct tooth morphotypes, including the first reports of conical‐toothed pliosaurids from the latest Jurassic and earliest Cretaceous. This challenges the hypothesis that only one lineage of pliosaurids crossed the Jurassic–Cretaceous boundary. It appears that conical‐toothed pliosaurids co‐existed with their trihedral‐toothed relatives for at least 25 million years during the latest Jurassic and earliest Cretaceous. In fact, our quantitative analyses indicate that pliosaurids reached their maximal dental disparity during this interval, showing little evidence of turnover associated with the Jurassic–Cretaceous transition. Instead, disparity decreased later in the Early Cretaceous, with the disappearance of trihedral‐toothed forms in the Barremian.
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The Jurassic-Cretaceous (J/K) and Cretaceous-Paleogene (K/Pg) boundaries/transitions are found in Pakistan especially well exposed on the western continental margin of the Indo-Pakistan plate (part of Gondwana) like Kirthar, Sulaiman and Kohat and Potwar basins. Its lithology is variable both lateral and also vertical. The J/K and K/Pg transitions are represented by terrestrial and marine strata like laterite, bauxite, vary colored shale, sandstones and conglomerates and rare limestone beds. Mesozoic vertebrates found so far belong to archosaurs like poripuchian titanosaurs (sauropods), theropods, mesoeucrocodiles, pterosaurs, snake and bird are briefly overviewed here.
Paleogene
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Cenomanian
Aptian
Ammonite
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Theropoda
Endocast
Cranial nerves
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Dinoflagellate
Lithology
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