Theropod courtship: large scale physical evidence of display arenas and avian-like scrape ceremony behaviour by Cretaceous dinosaurs

Relationships between non-avian theropod dinosaurs and extant and fossil birds are a major focus of current paleobiological research. Despite extensive phylogenetic and morphological support, behavioural evidence is mostly ambiguous and does not usually fossilize. Thus, inferences that dinosaurs, especially theropods displayed behaviour analogous to modern birds are intriguing but speculative. Here we present extensive and geographically widespread physical evidence of substrate scraping behavior by large theropods considered as compelling evidence of "display arenas" or leks, and consistent with "nest scrape display" behaviour among many extant ground-nesting birds. Large scrapes, up to 2 m in diameter, occur abundantly at several Cretaceous sites in Colorado. They constitute a previously unknown category of large dinosaurian trace fossil, inferred to fill gaps in our understanding of early phases in the breeding cycle of theropods. The trace makers were probably lekking species that were seasonally active at large display arena sites. Such scrapes indicate stereotypical avian behaviour hitherto unknown among Cretaceous theropods, and most likely associated with terrirorial activity in the breeding season. The scrapes most probably occur near nesting colonies, as yet unknown or no longer preserved in the immediate study areas. Thus, they provide clues to paleoenvironments where such nesting sites occurred

Myotis rufoniger genome sequence and analyses: M-rufoniger's genomic feature and the decreasing effective population size of Myotis bats

Myotis rufoniger is a vesper bat in the genus Myotis. Here we report the whole genome sequence and analyses of the M. rufoniger. We generated 124 Gb of short-read DNA sequences with an estimated genome size of 1.88 Gb at a sequencing depth of 66x fold. The sequences were aligned to M. brandtii bat reference genome at a mapping rate of 96.50% covering 95.71% coding sequence region at 10x coverage. The divergence time of Myotis bat family is estimated to be 11.5 million years, and the divergence time between M. rufoniger and its closest species M. davidii is estimated to be 10.4 million years. We found 1,239 function-altering M. rufoniger specific amino acid sequences from 929 genes compared to other Myotis bat and mammalian genomes. The functional enrichment test of the 929 genes detected amino acid changes in melanin associated DCT, SLC45A2, TYRP1, and OCA2 genes possibly responsible for the M. rufoniger's red fur color and a general coloration in Myotis. N6AMT1 gene, associated with arsenic resistance, showed a high degree of function alteration in M. rufoniger. We further confirmed that the M. rufoniger also has batspecific sequences within FSHB, GHR, IGF1R, TP53, MDM2, SLC45A2, RGS7BP, RHO, OPN1SW, and CNGB3 genes that have already been published to be related to bat's reproduction, lifespan, flight, low vision, and echolocation. Additionally, our demographic history analysis found that the effective population size of Myotis clade has been consistently decreasing since similar to 30k years ago. M. rufoniger's effective population size was the lowest in Myotis bats, confirming its relatively low genetic diversity

Bird tracks from the Green River Formation (Eocene) of Utah: ichnotaxonomy, diversity, community structure and convergence

Abundant well-preserved bird tracks from lacustrine Green River Formation (Eocene) deposits in Utah, are diverse and paleoecologically significant, but remain poorly known. Three of the four previously reported morphotypes (A-D) are named here for the first time with two representing new ichnotaxa. In order of increased footprint length (L) the ichnotaxa are: cf. Avipeda phoenix (L\ua0=\ua02.0\ua0cm); Quadridigitus semimembranus ichnogen. et ichnosp. nov. (L\ua0=\ua0~3.5\ua0cm); Jindongornipes falkbuckleyi ichnosp. nov. (L\ua0~\ua08.0\ua0cm); and previously named, web-footed Presbyornithiformipes feduccii (L\ua0=\ua09.5\ua0cm). Collectively these avian ichnotaxa, associated invertebrate traces including ubiquitous nematode trails (Cochlichnus), and other rarer, small tetrapod tracks represent the “shorebird” ichnofacies or ichnocoenosis. However, the local track assemblages from the Uinta Basin do not correspond to the avian body fossil record from multiple Green River basins in the larger region. Thus, both records are essential for a cumulative picture. The Green River ichnotaxa are morphologically similar to those from lake basins in the Korean Cretaceous, and modern shorebird assemblages. As modern shorebirds are not known from Cretaceous or Eocene body fossils, the most plausible explanation is community convergence, among taxonomically disparate, but ecologically convergent trackmakers. Community convergence concepts help refine the ichnofacies paradigm