Vol. 2 No. 2 (2021): Biosis: Biological Systems

The southern edge of Sichuan Basin has a long-standing folklore about the Tian Ji Stone, which actually tells of the theropod tracks. Here we describe a new Tian Ji track site named Xinglongwan in Chishui, Guizhou Province, China. Two kilometers away from the old site recorded in 2011, the later with cf. Irenesauripus isp. are morphologically different from the Xinglongwan theropod tracks. The tridactyl tracks from Xinglongwan site have been assigned to the cf. Eubrontes. Didactyl tracks in the Xinglongwan site, which are the first discovery of deinonychosaurian tracks in Guizhou Province, are assigned to the Velociraptorichnus. Both tracks were recorded in the report about ichnofauna in Jiaguan Formation, representing the diversity of theropod tracks in Sichuan Basin. The authors also briefly discuss the preservation mode and potential external-morphological changes of cf. Eubrontes and Velociraptorichnus from Xinglongwan site.

Elizabeth Pym wrote a letter in 1742 from the island of Nevis, in the Caribbean Sea, to Peter Collinson in London, describing various botanical samples she was sending him, including two coffee plants. The letter was found inside Volume II of Sir Hans Sloane’s “A Voyage to the Islands Madera …” housed at Oak Spring Garden Library in Virginia. Collinson received both volumes as gifts, with Volume I inscribed to him by Admiral Sir Charles Wager and Volume II inscribed by Sloane. The letter serves as a rare example documenting the collection of botanical specimens by a woman in the New World.

Recent studies have identified numerous pathologies in the cranial domes of pachycephalosaurid dinosaurs. These studies utilized CT images of domes to identify secondary woven bone and sclerosis associated with the pathologies. These features were critical for diagnosing post-traumatic osteomyelitis, which supported the head-butting behaviour hypothesis. However, conventional CT image resolution may not be sufficient to identify secondary woven bone or sclerotic bone in fossil specimens. UALVP 8504 (cf. Foraminacephale brevis), a dome possessing putative bone lesions, was thin-sectioned and micro-CT scanned. Thin sections revealed the lesions are lytic, without any secondary woven bone or sclerosis, falsifying the diagnosis of osteomyelitis. The morphology and histology of the lesions of UALVP 8504 are not diagnostic and resemble both post-traumatic and non-traumatic lesions.  However, UALVP 8504 possesses shifted vascular canals (repositioning via remodeling, which maintains anatomical position throughout ontogeny) that are decoupled from growth (), and drifting osteons (secondary osteons where resorption occurs longitudinally and transversely). These demonstrate that the dome has sustained external mechanical loading, likely resulting from an impact or multiple impacts, consistent with the head-butting hypothesis. These impacts may have damaged overlying soft tissues and formed the lesions along the surface. Therefore, we suspect that the pathologies in UALVP 8504 are post-traumatic.

Previously known theropod dinosaur footprints preserved as natural casts in the Tuchengzi Formation, on a rock wall beside the railway in Nanshuangmiao Village, Shangbancheng Town, Chengde City, were originally assigned to ichnogenus Anchisauripus and tentatively attributed to oviraptosaurs. The assemblage was restudied in more detail by examining the entire assemblage of 55 tracks associated with two horizons. The size range of the 27 measured tracks suggests a more diverse grallatorid–eubrontid assemblage and potentially greater diversity of theropod trackmakers. The label Anchisauripus, which has fallen into disuse in some recent literature, implies trackmakers of medium shape and size in the grallatorid–eubrontid morphological spectrum. However, given the presence of other theropod ichnotaxa in the Jurassic to Early Cretaceous strata of the Tuchengzi Formation and time equivalent units we suggest that explicit reference to the Grallator-Anchisauripus-Eubrontes (GAE) plexus, or simply the term Grallator-Eubrontes plexus be confined to Lower Jurassic assemblages as originally defined and intended. Further study centered on the 16 known Tuchengzi assemblages and older theropod ichnfaunas is necessary to confirm or refute the degree to which grallatorid–eubrontid assemblages from these different epochs are similar or convergent. Even if the tracks are morphologically very similar inferences regarding trackmaker identity are problematic because the same theropodan trackmaker species, genera or even families were not present in both epochs.

In recent years the number of track sites discovered and reported from the Lower Cretaceous Jiaguan Formation, Sichuan Basin has increased steadily. Here we report on the 20^th and 21^st sites which are situated in unusual locations in a cave and on a steep bedding plane surface in association with Tang Dynasty grottoes. The ichnofauna is represented by two small assemblages which are both theropod-dominated. Due to sub-optimal preservation, the tracks are identified only as grallatorid and small and larger eubrontid, with Paracorpulentapus also tentatively recognized.

We examined the evolutionary relationship of the ASPM (abnormal spindle-like microcephaly associated) and MCPH1 (microcephalin-1) genes with brain volume among humans and other primates. We obtained sequences of these genes from 14 simiiform species including hominins. Two phylogenetic analyses of ASPM exon 3 and MCPH1 exons 8 and 11 were performed to maximize taxon sampling or sequence extension to compare the nucleotide substitution and encephalization rates, and examine signals of selection. Further assessment of selection among humans was done through the analysis of non-synonymous and synonymous substitutions (d_N/d_S), and linkage disequilibrium (LD) patterns. We found that the accelerated evolution of brain size in hominids, is related to synchronic acceleration in the substitution rates of ASPM and MCPH1, and to signals of positive selection, especially in hominins. The d_N/d_S and LD analyses in Homo detected sites under positive selection and some regions with haplotype blocks at several candidate sites surrounded by blocks in LD-equilibrium. Accelerations and signals of positive selection in ASPM and MCPH1 occurred in different lineages and periods being ASPM more closely related with the brain evolution of hominins. MCPH1 evolved under positive selection in different lineages of the Catarrhini, suggesting independent evolutionary roles of this gene among primates.