Genetic interpretation of fish swimming trails and calculation of fish-body length in Late Triassic Hengshan, Shaanxi Province, China

The rhynchosaur Rhynchosaurus articeps Owen, 1842, from the Middle Triassic of Grinshill, northern Shropshire, England, was a small reptile, about 0.5 m long. About 17 individual animals are represented by skulls, complete skeletons and partial skeletons, and these have permitted detailed restorations. The skull (60-80 mm long) is low and broad at the back, and it shows all of the typical rhynchosaur features of beak-like premaxillae, single median naris, fused parietal, broad maxillary tooth plate and dentary, both with multiple rows of teeth, and a deep lower jaw. The skeleton shows adaptations for fast terrestrial locomotion with a semi-erect hindlimb posture and for scratch-digging with the hind-foot. The skeleton is relatively more slender than that of most other middle and late Triassic rhynchosaurs, but this is probably an allometric effect of its much smaller size (they are typically 1-2 m long). A further species of Rhynchosaurus from Warwick, named here R. brodiei , is represented by 15 specimens of partial skulls, tooth-bearing elements, and isolated postcranial bones. It was slightly larger than R. articeps , with a typical skull length of 90 mm, and estimated body length of 0.6 m, but the skull length ranged up to 140 mm. It differs from R. articeps in having a much larger jugal in the cheek area, and in the greater height and breadth of the skull. The isolated maxillary fragments from Bromsgrove probably also belong to R. brodiei . The third species of Rhynchosaurus from Devon, named here R. spenceri , is now known from numerous specimens of at least 25 individuals, most of which were collected recently. These show a range in estimated skull length from 40 to 170 mm, but most specimens are at the upper end of that range, with an average skull length of 140 mm, and an estimated total body length of 0.9-1.0 m R. spenceri differs from R. articeps and R. brodiei in having a skull that is broader than it is long (otherwise a character of late Triassic rhynchosaurs), and it shares the large jugal character with R. brodiei . Teeth are not well preserved in R. articeps, but several specimens of R. brodiei and R. spenceri give detailed information. The pattern of wear, and the nature of the jaw joint, suggest that Rhynchosaurus had a precision-shear bite, as in other rhynchosaurs, with no back and forwards motion. The maxilla had two grooves, a major and a minor one, which received two matching ridges of the dentary on occlusion. The multiple rows of teeth on maxilla and dentary, and the surrounding bone, wore down as uniform units. The diet was probably tough vegetation, which was dug up by scratch-digging, raked together with the hands or the premaxillary beak, and manipulated in the mouth by a strong tongue. Rhynchosaurus is found variously in fluvial-intertidal deposits with evidence of desiccation (Grinshill, Warwick, Bromsgrove), and fluvial-aeolian deposits laid down in arid conditions with occasional flash floods (Devon). The bones have generally been transported (Warwick, Bromsgrove, Devon), but the Grinshill specimens are largely complete and undisturbed. The associated floras and faunas at Warwick, Bromsgrove, and Devon include pteridophytes, gymnospermopsids, bivalves, scorpions, freshwater fish, temnospondyl amphibians and reptiles (macrocnemids, thecodontians, ?procolophonids). Rhynchosaurs are archosauromorph diapsids, possibly related to the enigmatic Trilophosaurus, and a sister group to Prolacertiformes + Archosauria. A cladistic analysis of Rhynchosauria reveals one major subgroup, the Hyperodapedontinae ( Hyperodapedonand and Scaphonyx ), which is late Triassic in age. The earlier rhynchosaurs, including the middle Triassic Stenaulorhynchus and Rhynchosaurus , appear to form successively closer outgroups to the Hyperodapedontinae. The three species of Rhynchosaurus share only one possible synapomorphy in comparison with Stenaluorhynchus : The dentary is well over half the length of the lower jaw. The ‘Rhynchosaurinae’ ( Stenaulorhynchus and Rhynchosaurus ) was not established as a monophyletic group in the present analysis. These two genera share two postulated synapomorphies: the occipital condyle lies well in front of the quadrates, and there are two grooves on the maxilla and two ridges on the dentary. A third postulated synapomorphy, the presence of a single row of teeth on the pterygoid, has not been confirmed in this study for either Rhynchosaurus or Stenaulorhynchus . However, these postulated synapomorphies are outweighed by the synapomorphies that Rhynchosaurus shares with the Hyperodapedontinae. The specimens of Rhynchosaurus have been used as biostratigraphic indicators for the English middle Triassic, indicating Anisian to early Ladinian ages. The three species can be arranged in a sequence from ‘most prim itive’ to ‘most advanced’, but this cannot be used confidently to give a stratigraphic sequence.

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A Classification Method for Fish Swimming Behaviors under Incremental Water Velocity for Fishway Hydraulic Design

Water ◽

10.3390/w11102131 ◽

2019 ◽

Vol 11 (10) ◽

pp. 2131 ◽

Cited By ~ 2

Author(s):

Mu ◽

Cao ◽

Gong ◽

Baiyin ◽

Li

Keyword(s):

Body Length ◽

Grass Carp ◽

Fish Passage ◽

Water Velocity ◽

Classification Method ◽

Water Tank ◽

Fish Swimming ◽

Hydraulic Design ◽

Burst Swimming ◽

Velocity Changes

In fishway design, the combination of fish swimming behaviors and suitable fishway hydraulic characteristics increases the fish passage efficiency. In this study, the most representative grass carp among the “four major Chinese carps” was selected. Under conditions similar to the time period for feeding migration, juvenile grass carps were targeted to study the swimming characteristic indicators (i.e., critical and burst swimming speeds) and swimming behaviors that were closely associated with fishway hydraulic design using the incremental water velocity method in a homemade test water tank. (1) The study results reveal that both the absolute critical (Ucrit) and burst (Uburst) swimming speeds increased linearly with increasing body length and both the relative critical (U’crit) and burst (U′burst) swimming speeds decreased linearly with increasing body length. There existed a quantitative relationship between Uburst and Ucrit, which could facilitate the fishway hydraulic design. (2) This study analyzed the effects of water velocity changes on fish swimming behaviors and proposed a classification method for four fish swimming behaviors—swimming freely, staying, dashing at a long distance, and dashing at a short distance—of tested fish during the process of adapting to water velocity changes interspersed with one another. The entire swimming process under the incremental water velocity was divided into four stages. (3) This study suggests that the maximum water velocity of the mainstream in a fishway using grass carp as the major passage fish should not exceed 52–60% Uburst at stage 1. For the high-water velocity areas of a fishway, such as vertical slots and orifices, the optimal water velocity should not be higher than 76–79% Uburst at stage 2 and should absolutely not exceed 90–96% Uburst at stage 3.

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Geological Controls on Mineralogical Characteristic Differences of Coals from the Main Coal Fields in Shaanxi, North China

Energies ◽

10.3390/en14237905 ◽

2021 ◽

Vol 14 (23) ◽

pp. 7905

Author(s):

Wei Yuan ◽

Jing Li ◽

Xinguo Zhuang ◽

Guanghua Yang ◽

Lei Pan

Keyword(s):

Middle Jurassic ◽

North China ◽

Ordos Basin ◽

Shaanxi Province ◽

Late Triassic ◽

Sediment Provenance ◽

Coal Resources ◽

Mineral Characteristics ◽

Lagoon Environment ◽

Coal Fields

Shaanxi is among the provinces with abundant coal resources in North China. These enormous coal resources (approx. 4143 Gt) are widely distributed in the Ordos Basin and its marginal fold belts. The main coal-bearing strata consist of the late Carboniferous Taiyuan Formation, the early Permain Shanxi Formation, the late Triassic Wayaobao Formation, and the middle Jurassic Yan’an Formation, which were respectively deposited in coastal plains and a lagoon environment, a continental environment, an inland open lake and a confined lake environment. The Permo-Carboniferous coals are low volatile bituminous and characterized by relatively high vitrinite content, which decreases from south to north, and from the lower coal seams upwards. By contrast, the late Triassic and middle Jurassic coals are highly volatile bituminous, but are respectively characterized by relatively high vitrinite and high inertinite content. Minerals in the Permo-Carboniferous coals, the late Triassic coals, and the middle Jurassic coals, are respectively dominated by kaolinite and calcite, quartz and kaolinite, and quartz and calcite. Furthermore, contemporary coals deposited in different coal fields or even different mines of the same coal field present different mineral characteristics. The Permain Shanxi Formation coals from the Shanbei C-P coalfield in the north of Shaanxi Province are characterized by higher kaolinite and lower carbonate contents compared to those from the Weibei C-P coalfield in the south of Shaanxi Province. The distinctive mineralogical characteristics of coals formed in different coalfields and different geological ages were ascribed to integrated influences of different terrigenous detrital input from sediment provenance, sedimentary settings (e.g., subsidence rate, sea transgression, and regression process), and hydrothermal activities.

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The first Triassic ‘Protodonatan’ (Zygophlebiidae) from China: stratigraphical implications

Geological Magazine ◽

10.1017/s0016756816000625 ◽

2016 ◽

Vol 154 (1) ◽

pp. 169-174 ◽

Cited By ~ 6

Author(s):

D. R. ZHENG ◽

A. NEL ◽

B. WANG ◽

E. A. JARZEMBOWSKI ◽

S.-C. CHANG ◽

...

Keyword(s):

Upper Triassic ◽

Northwestern China ◽

Shaanxi Province ◽

Late Triassic ◽

The Family ◽

Insect Fossils ◽

Geochronological Evidence ◽

High Diversity

AbstractThe clade Triadophlebioptera within the Odonatoptera greatly diversified and became widely distributed worldwide during the Triassic. Although abundant insect fossils have been reported from the Triassic of China, no Triassic dragonflies have been recorded. In this paper,Zygophlebia tongchuanensissp. nov., the first species of Zygophlebiidae discovered outside the Madygen Formation of Kyrgyzstan, is described from the Middle–Upper Triassic Tongchuan Formation of Shaanxi Province, northwestern China. The discovery extends the distribution of the family Zygophlebiidae in Asia, indicating a high diversity of Triadophlebioptera during Middle–Late Triassic times. Combined with the palaeontological and geochronological evidence, the age of the Tongchuan Formation is considered to be Anisian – Early Carnian, and the insect-bearing layers are considered to be Ladinian.

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Burst-and-coast swimmers optimize gait by adapting unique intrinsic cycle

Communications Biology ◽

10.1038/s42003-020-01521-z ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Gen Li ◽

Intesaaf Ashraf ◽

Bill François ◽

Dmitry Kolomenskiy ◽

Frédéric Lechenault ◽

...

Keyword(s):

Numerical Simulations ◽

Body Length ◽

High Speed ◽

Physical Mechanism ◽

Full Description ◽

Fish Swimming ◽

Fish Muscles

AbstractThis paper addresses the physical mechanism of intermittent swimming by considering the burst-and-coast regime of fish swimming at different speeds. The burst-and-coast regime consists of a cycle with two successive phases, i.e., a phase of active undulation powered by the fish muscles followed by a passive gliding phase. Observations of real fish whose swimming gait is forced in a water flume from low to high speed regimes are performed, using a full description of the fish kinematics and mechanics. We first show that fish modulate a unique intrinsic cycle to sustain the demanded speed by modifying the bursting to coasting ratio while maintaining the duration of the cycle nearly constant. Secondly, we show using numerical simulations that the chosen kinematics by correspond to optimized gaits for swimming speeds larger than 1 body length per second.

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