Biosis: Biological Systems

Stratigraphic Lexicon: The Onshore Cenozoic Sedimentary Formations of The Republic of Panama

2021-02-25T01:39:27+08:00

The stratigraphic knowledge of Panama was, until now, spread over hundreds of scientific/geologic publications written during the past 120 years. The construction of the Panama Canal during the early twentieth century helped galvanizing the engineering and geological disciplines to understand the tectonic, sedimentation and biodiversity of the Cenozoic Era in this part of the world. Later, few petroleum companies arrived on the scene and contributed to our knowledge of the sub-surface. The past thirty years saw a surge of studies by many institutions in areas away from the Canal, such as in Darien, Azuero Peninsula, Bocas del Toro, and the Burica Peninsula near the Costa Rica Border. Our most recent knowledge came from the widening of the Panama Canal between 2007 and 2016. It is from all these older and recent studies that the present Lexicon draws its content. It provides the historical background of all described geological units in Panama and summarizes the lithological and paleontological knowledge of each units in an easy-to-search format.

Theropod footprints from the Lower Cretaceous Cangxi Formation in the Northern Margin of the Sichuan Basin, China

2021-03-15T21:36:08+08:00

A single well-preserved theropod trackway identified as Eubrontes was discovered in the Lower Cretaceous (Berriasian-Valanginian) Cangxi Formation on the northern margin of the Sichuan Basin This is the first report of tracks from this formation. The occurrence is consistent with reports of theropod dominated ichnofaunas from broadly coeval deposits such as the Feitianshan Formation in southern parts of the basin. There is growing evidence that Eubrontes and Eubrontes-like tracks are common in the Lower Cretaceous of Sichuan Province.

A new genus of Apsilocephalidae (Diptera) in Mid-Cretaceous Burmese amber

2021-02-10T23:05:30+08:00

A new genus and species of apsilocephalid flies, Cascomixticus tubuliferous gen. et sp. nov. (Diptera: Asiloidea: Apsilocephalidae) is described from Burmese amber. Assignment to the Apsilocephalidae is based on the wing venation that is very similar to extant members of the family. The present fossil differs from known genera of this family by a long labellum bearing tactochemical papillae, a long tubular hypopharynx and a pointed labrum as well as the structure of the scape and pedicel. The long, tubular hypopharynx may have been used to obtain nectar from angiosperm flowers, however the function of the sharp-tipped labrum is unknown.

A Review of two Middle Jurassic Theropod Tracksites Discovered in the 1980s from Sichuan Basin

2021-02-20T11:13:15+08:00

Tracks from two sites in the Middle Jurassic Xintiangou Formation in the Wuma Village area, Wuhuang Township, Zizhong have been known and intermittently studied and excavated since the 1980s. The track-bearing surfaces were exposed by a combination of natural weathering and deliberate excavation by residents in a rural agricultural area. The surfaces were used as “threshing floors” for the processing of agricultural crops in an area subject to weathering under a humid sub-tropical climatic regime. Despite the negative effects of weathering on the quality of track preservation, the sites are historically significant in Chinese ichnology as the type areas for many controversially named theropod ichnotaxa. Subsequent researchers challenged the ichnotaxonomy as provincial and over-split, suggesting that many of the tracks, belong to well-known Lower Jurassic ichnogenera. The present study reviews these two sites, providing new information, and confirming that the tracks belong to the ichnogenera Grallator, Eubrontes and Kayentpus which are typical of the globally widespread Lower Jurassic tetrapod biochron. This suggests the Middle Jurassic ichnofauna in Sichuan is like Lower Jurassic ichnofaunas elsewhere. Previous efforts to transfer the ichnospecies to globally, better-known ichnogenera were important in reducing ichnogenus diversity, but did not reduce ichnosepcies diversity. Herein the ichnotaxa are reviewed and it is shown that the ichnospecies names have no utility for comparative study or in assessing assemblage diversity, or biochron composition. It is therefore proposed that the multiple ichnospecies names proposed based on tracks from these two localities can mostly be accommodated under the labels Grallator isp. indet., and Eubrontes isp. indet.

The Ecological Niche of Pistacia Vera L. (Anacardiaceae) in Central Asia: A Comprehensive Tool for Agromeliorative Planning

2021-01-26T16:45:38+08:00

A model of the ecological niche of the nut fruit Pistacia vera has been developed based on known locations in Central Asia and an analysis of abiotic environmental variables in order to map out the area of optimal conditions for both the wild and domesticated forms. The model reveals a much larger area of suitability for the species than it presently occupies. The list of key variables and their optimal ranges are compared with the known values of those which have been gathered from experiments on the ground and which are described in the available literature. Most of the optimal values modeled for the key variables appear to resemble the known experimental ranges. The meaning and impact of most of the key variables in relation to the species’ life cycle are found in the physiological and ecological peculiarities of P. vera’s development at different stages as described in the literature. Unexplained variables may imply a gap in our knowledge of the pistachio and its interrelations with the environment; and point the direction of further study of the biology of the pistachio. The value of the model is the potential application of the results along with existing practical recommendations regarding pistachio cultivation in order to establish guidelines regarding the conservation and commercial cultivation of P. vera in Kazakhstan.

Lower Cretaceous Dinosaur Trackways Exposed by Water Erosion in Sichuan Province, China

2021-02-20T11:06:27+08:00

A newly discovered saurischian dominated tracksite in the Lower Cretaceous Jiaguan Formation in southeastern Sichuan province reveals 13 sauropod trackway segments representing ichnogenus Brontopodus and three theropod trackways. This is a typical Type 1 Jiaguan Formation deposit dominated by tetrapod tracks with no significant tetrapod body fossils. The tracks occur in a river channel exposure of feldspathic quartz sandstone about 20–25 m wide and ~ 60 m long. The trackways are exposed on both banks but eroded away in the central channel area. The sauropod tracks represent relatively small animals with pes print lengths ranging from 24.5 cm to 33.9 cm. The theropod trackways include a large example (footprint length 46.5 cm with metatarsal traces) and two smaller parallel trackways with footprint lengths less than 20 cm. The author also discussed the erosion of tracks and trackways by water erosion, especially their morphological changes.