Birds share a number of unique features setting them apart from other vertebrates. These range from their anatomical adaptations to reproductive traits and behaviour. New fossil discoveries and advances in genomics and have shed light on the evolution of these remarkable differences. Michael Gross reports.
Gurvelus Âkhangaicus gen. & sp. nov. (Ardeosauridae)
Khereidia aptiana gen. & sp. nov. (Globauridae)Â
Naimanosaurus dinosauroaequalis Âgen. & sp. nov. (Paramacellodidae)
Classification of lizards of the infraorder Scincomorpha is discussed in the paper. The history and problems of studying Eoxantidae, Ardeosauridae, Globauridae, and Paramacellodidae fossil families from this infraorder are presented in more detail. New species from the AptianâAlbian deposits of Mongolia have been added to the lizard families listed above.
The Permian dicynodont records were previously rare in North China, but many dicynodont specimens have been collected from the Naobaogou Formation in Daqingshan area, Nei Mongol since 2009. Among these specimens, seven morphotypes have been identified, and they may represent seven different species: two of them are closely related to Daqingshanodon limbus, three or four are closely related to Jimusaria sinkianensis, and one may be closely related to Turfanodon. This study shows the dicynodonts also have a high diversity at the species level in North China.
Aquatic and terrestrial animals from various niches are preserved in same horizons.
Aquatic arthropods are characterized by low diversity and high to medium abundance.
Terrestrial insects are characterized by high diversity but low abundance.
Terrestrial insects are well-preserved and articulated as a result of rapid burial.
Mass mortality events triggered by volcano eruptions may have frequently occurred.
The Yanliao Biota contains numerous exceptionally preserved fossils of evolutionary importance, and one of the important fossil sites is the Daohugou area. However, the palaeoenvironment of this biota has not been fully studied. Here we present the first taphonomical and palaeoecological analysis of fossil abundance data from two newly excavated sites in the Daohugou area. Our study has investigated the taxonomic composition, specimen abundance, and size distribution patterns of invertebrate palaeocommunities, and corresponding taphonomical features, such as completeness, articulation and fossil orientation. Our results show that abundant aquatic and terrestrial organisms from various ecological niches are preserved in very thinly planar-laminated mudstone. Aquatic organisms of the two excavations are represented by low-diversity but high-density assemblages containing four species: the clam shrimp Triglypta haifanggouensis, the mayfly nymphs Fuyous gregarious and Shantous lacustris, and the water boatman Daohugocorixa vulcanica. Triglypta haifanggouensis dominates the fauna with carapace lengths ranging from 1.34âmm to 5.62âmm and mean size varying in time. Size distributions of different stratigraphic bedding planes vary between normal, bimodal and polymodal, implying multiple causes of death: reproductive senescence, and mass mortality events related to active volcanism or to rapid environmental fluctuations within the lake. Generally calm depositional conditions were repeatedly interrupted by weak currents, indicated by preferred plan-view orientations of aquatic insects on four out of nine investigated bedding planes. Changes in the community composition of aquatic arthropods relate to lake deepening or shallowing through time, or to different dispersal strategies after community breakdown. Terrestrial insects are highly diverse but less abundant. As a result of rapid burial, 49.8% of which are almost complete and articulated. Similarly, the flora surrounding the lake was rich, picturing a thriving forest-like ecosystem with moisture relation in a warm-temperate climate.