Histological analysis of Montealtosuchus allows to understand their fossildiagenesis.
The histological samples of Montealtosuchus were analyzed with SEM/EDS and Î-XRF.
The Montealtosuchus fossils bones are in majority composed by calcium and phosphorus.
Iron, vanadium and cerium were incorporated in the bones of Montealtosuchus during eodiagenesis.
The histological analysis of fossil bones allows a taphonomic approach, especially to fossildiagenesis. We studied the femur, vertebra, and osteoderm of the crocodyliform Montealtosuchus arrudacamposi (Adamantina Formation; Late Cretaceous), to make inferences of the sequence of the diagenetic processes. Cross-sections of the bones and the rock matrix that fills the medullar cavity were analyzed under a scanning electron microscopy with compositional analysis (SEM/EDS) and Î-X-Ray fluorescence (Î-XRF). The microstructural pattern of the femur and vertebra was similar, with a transition from vascularized fibrolamellar internal cortex, with reticular and longitudinal canals to zonal lamellar in the outer, and a medullary cavity portion filled with quartz and other mineral grains. The osteoderm, however, presented a less vascularized cortex. In all samples were found the External Fundamental System (EFS), secondary osteons in the internal cortex and spongy tissue, and the transition from a fibrolamellar to a lamellar tissues, indicating that the individual reached ontogenetic maturity (adult/senescent) before they died. The compositional results showed that the samples mainly comprised calcium and phosphorus, which were homogeneously distributed. However, we inferred that these elements occurred during the formation of recrystallized and authigenic minerals. Iron, vanadium, and cerium are the elements found that occurred in the composition of the fossil remains during early diagenesis, and this process was observed to extend to the late diagenesis. Cerium was homogeneously distributed and incorporated to authigenic apatite. Iron and vanadium were restricted to the cortex. The presence of authigenic apatite and Rare Earth Elements (REEs) in the samples supported that the diagenetic environment of the Adamantina Formation was alkaline. Furthermore, it suggested an association with a groundwater environment that have allowed and facilitated the well preservation of fossil vertebrates in this geological formation.
Sauropterygia, one of the main clades of Mesozoic marine reptiles, diversified shortly after the Permo-Triassic biotic crisis and afterwards remained one of the major components of Early Triassic and later Mesozoic marine ecosystems. On the other hand, actual specimens of marine reptiles of Olenekian age are still rare in the fossil record, coming only from a few localities worldwide. Here we describe associated remains of a larger marine reptile of around 4 m body length, with nothosauroidean affinities from the Sulphur Mountain Formation exposed at the L cirque locality of Wapiti Lake area in British Columbia. Although the specimen records only scattered parts of the posterior vertebral column, some gastral ribs and most notably, the proximal portion of one hind limb together with a fan-shaped ischium, it represents one of the oldest records of Sauropterygia and larger representatives of aff. Nothosauroidea specifically, as well as the northernmost occurrence of such animals in the Triassic. As such, the new specimen is important for understanding the biogeography and early evolution of the group and that of Sauropterygia, in general.
IvÃn Meza-VÃlez & JosÃ P. OâGorman (2019)
First Plesiosaurian record (Diapsida; Sauropterygia) from the La Herradura Formation, (ValanginianâHauterivian), Morro Solar, Peru.
Cretaceous Research Article 104247 (advance online publication)
doi: https://doi.org/10.1016/j.cretres.2019.104247 https://www.sciencedirect.com/science/article/pii/S0195667119301818
We report the first plesiosaur remains (Diapsida, Sauropterygia) from Peru, recovered from Lower Cretaceous rocks cropping out in Morro Solar, within Lima city (La Herradura Formation, ValanginianâHauterivian). The material is restricted to an undetermined propodium, fragmentary vertebrae and ilium, being identified as a Plesiosauria, with putative affinities to Leptocleididae or Elasmosauridae. This record provides further data on the group in the Southeastern Pacific.
First evidence of conical-toothed pliosaurids (Reptilia, Sauropterygia) in the Hauterivian of the Northern Calcareous Alps, Austria.
Isolated tooth crown originates from the upper Hauterivian Balearites balearis Zone.
Finding sheds light on the diversity and distribution of pliosaurids in the Lower Cretaceous.
First pliosaur from Austria and the first evidence of Cretaceous pliosaurids from the entire Alpine arc.
The first pliosaurid finding in Austria is described from the Lower Cretaceous (Hauterivian) pelagic to hemipelagic limestone succession of the Northern Calcareous Alps (Bajuvaric Langbath Zone). The isolated tooth crown originates from the upper Hauterivian Balearites balearis Zone (Balearites angulicostatus Subzone). The finding sheds light on the diversity and distribution of pliosaurids in the Lower Cretaceous, being only the second occurrence of conical-toothed pliosaurid in the Hauterivian worldwide and the first pliosaur from Austria. The pliosaur reported is the first from the entire northern, central and western Alpine chain, and the first evidence of Cretaceous pliosaurids from the entire Alpine arc.
Fossil turtles are one of the least studied clades in regard to endocranial anatomy. Recently, the use of non-invasive technologies, such as radiographic computed tomography (CT), increased the knowledge of the neuroanatomy of several extinct and extant taxa. Here, we provide the description of the nasal cavity, cranial endocast, and inner ear of the stem turtle Naomichelys speciosa based on digital 3D reconstructions. This terrestrial form is characterized by a nasal cavity with anteroposteriorly elongated vestibulum and a large cavum nasi proprium, traits typically related to terrestrial habits. The large olfactory region of the cavum nasi proprium suggests that olfaction was probably the most important sense for this species. Our description of N. speciosa adds novel information to the knowledge of endocranial anatomy in early turtle evolution and provides an important foundation for future analyses and comparisons.
Kyung Soo Kim, Jong Deock Lim, Martin G. Lockley, Dong Hee Kim, Laura PiÃuela & Jae Sang Yoo (2019)
Largest Cretaceous lizard track assemblage, new morphotypes and longest trackways comprise diverse components of an exceptional Korean Konservat-LagerstÃtten ichnofauna.
Scientific Reports 9, Article number: 13278
A newly discovered assemblage of lizard tracks from the Lower Cretaceous Jinju Formation (Sindong Group, Gyeongsang Basin) Korea is the largest yet reported from the Cretaceous. It consists of at least 95 tracks comprising five trackways, including a meter-long trackway (T1) with 50 footprints assigned to the new ichnotaxon Neosauroides innovatus ichnosp. nov. Two other trackways (T2 and T3) are designated N. innovatus paratypes characterized by strong heteropody, relatively wide trackways and small narrow manus tracks. These morphological characteristics distinguish Neosauroides innovatus from the previously reported lizard trackways Sauripes hadongensis from the Hasandong Formation and Neosauroides koreaensis from the Haman Formation, both also from the Gyeongsang Basin. These three lizard track assemblages from the Korean Cretaceous constitute the entire global lizard track record for this period. The Mesozoic record of lizard tracksites is more localized than the lizard body fossil record. This limited distribution suggests bias in the track record and the fossil record more generally. However, due to deposition of fine-grained substrates, suitable for high definition track registration, the Jinju Formation is increasingly well known as an ichnological window on small tetrapod activity and based on diversity, abundance and high-quality preservation, is regarded as an exceptional Konservat-LagerstÃtten.
Lotta Salomies, Julia Eymann, Imran Khan & Nicolas Di-PoÃ (2019)
The alternative regenerative strategy of bearded dragon unveils the key processes underlying vertebrate tooth renewal.
eLife 8: e47702
Deep understanding of tooth regeneration is hampered by the lack of lifelong replacing oral dentition in most conventional models. Here, we show that the bearded dragon, one of the rare vertebrate species with both polyphyodont and monophyodont teeth, constitutes a key model for filling this gap, allowing direct comparison of extreme dentition types. Our developmental and high-throughput transcriptomic data of microdissected dental cells unveils the critical importance of successional dental lamina patterning, in addition to maintenance, for vertebrate tooth renewal. This patterning process happens at various levels, including directional growth but also gene _expression_ levels, dynamics, and regionalization, and involves a large number of yet uncharacterized dental genes. Furthermore, the alternative renewal mechanism of bearded dragon dentition, with dual location of slow-cycling cells, demonstrates the importance of cell migration and functional specialization of putative epithelial stem/progenitor niches in tissue regeneration, while expanding the diversity of dental replacement strategies in vertebrates.