A newly discovered collection of rare dinosaur tracks is helping scientists shed light on some of the biggest animals ever to live on land.
Hundreds of footprints and handprints made by plant-eating sauropods around 170 million years ago have been found on the Isle of Skye in Scotland.
The discovery - which is the biggest dinosaur site yet found in Scotland - helps fill an important gap in the evolution the huge, long-necked animals, which were the biggest of the dinosaurs.
Scientists at the University of Edinburgh identified the tracks in layers of rock, which would have been at the bottom of a shallow, salt water lagoon when the prints were made.
By analysing the structure of the footprints, the team found that the dinosaurs were early, distant relatives of more well-known species, such as Brontosaurus and Diplodocus. The Skye dinosaurs likely grew to at least 15 metres in length and weighed more than 10 tonnes.
The footprints - the largest of which is 70 cm in diameter - are the first sauropod tracks to be found in Scotland. Until now, the only evidence that sauropods lived in Scotland came from a small number of bone and teeth fragments.
Fossils from the Middle Jurassic Period are extremely rare, and the Isle of Skye is one of the few places in the world where they can be found.
The discovery is helping scientists to reimagine the habitats and lifestyles of the world's biggest dinosaurs. Together with similar tracks found recently in other parts of the world, the Skye trackways reveal that sauropods spent lots of time in coastal areas and shallow water. It was previously thought that large dinosaurs were purely land-dwellers.
Evidence for a Mid-Jurassic Adaptive Radiation in Mammals
Authors:
Close et al
Abstract:
A series of spectacular discoveries have transformed our understanding of Mesozoic mammals in recent years. These finds reveal hitherto-unsuspected ecomorphological diversity that suggests that mammals experienced a major adaptive radiation during the Middle to Late Jurassic [ 1 ]. Patterns of mammalian macroevolution must be reinterpreted in light of these new discoveries [ 1–3 ], but only taxonomic diversity and limited aspects of morphological disparity have been quantified [ 4, 5 ]. We assess rates of morphological evolution and temporal patterns of disparity using large datasets of discrete characters. Rates of morphological evolution were significantly elevated prior to the Late Jurassic, with a pronounced peak occurring during the Early to Middle Jurassic. This intense burst of phenotypic innovation coincided with a stepwise increase in apparent long-term standing diversity [ 4 ] and the attainment of maximum disparity, supporting a “short-fuse” model of early mammalian diversification [ 2, 3 ]. Rates then declined sharply, and remained significantly low until the end of the Mesozoic, even among therians. This supports the “long-fuse” model of diversification in Mesozoic therians. Our findings demonstrate that sustained morphological innovation in Triassic stem-group mammals culminated in a global adaptive radiation of crown-group members during the Early to Middle Jurassic.
Short note on a non-pterodactyloid pterosaur from Upper Jurassic deposits of Inner Mongolia, China
Authors:
Cheng et al
Abstract:
Daohugou is an important locality of the Jurassic Yanliao Biota, where only two pterosaurs have been described so far (Jeholopterus and Pterorhynchus). Here we report a new genus and species, Daohugoupterus delicatus gen. et sp. nov. (IVPP V12537), from this region, consisting of a partial skeleton with soft tissue. The skull is laterally compressed, differing from Jeholopterus. The antorbital fenestra is larger than in Pterorhynchus. The upper temporal fenestra is unusually small. The short cervical vertebrae bearing cervical ribs indicate that it is a non-pterodactyloid flying reptile. The sternal plate is triangular, being much wider than long. The deltopectoral crest of humerus is positioned proximally and does not extend further down the shaft, a typical feature of basal pterosaurs. Daohugoupterus also differs from the wukongopterids and scaphognathids from the Tiaojishan Formation at Linglongta, regarded to be about the same age as the Daohugou Bed. The new specimen increases the Jurassic non-pterodactyloid pterosaur diversity of the Yanliao Biota and is the smallest pterosaur from Daohugou area so far.
Resolution of deep angiosperm phylogeny using conserved nuclear genes and estimates of early divergence times
Authors:
Zeng et al
Abstract:
Angiosperms are the most successful plants and support human livelihood and ecosystems. Angiosperm phylogeny is the foundation of studies of gene function and phenotypic evolution, divergence time estimation and biogeography. The relationship of the five divergent groups of the Mesangiospermae (~99.95% of extant angiosperms) remains uncertain, with multiple hypotheses reported in the literature. Here transcriptome data sets are obtained from 26 species lacking sequenced genomes, representing each of the five groups: eudicots, monocots, magnoliids, Chloranthaceae and Ceratophyllaceae. Phylogenetic analyses using 59 carefully selected low-copy nuclear genes resulted in highly supported relationships: sisterhood of eudicots and a clade containing Chloranthaceae and Ceratophyllaceae, with magnoliids being the next sister group, followed by monocots. Our topology allows a re-examination of the evolutionary patterns of 110 morphological characters. The molecular clock estimates of Mesangiospermae diversification during the late to middle Jurassic correspond well to the origins of some insects, which may have been a factor facilitating early angiosperm radiation.
