Rapid neck elongation in Sauropterygia (Reptilia: Diapsida) revealed by a new basal pachypleurosaur from the Lower Triassic of China.

Neck elongation has appeared independently in several tetrapod groups, including giraffes and sauropod dinosaurs on land, birds and pterosaurs in the air, and sauropterygians (plesiosaurs and relatives) in the oceans. Long necks arose in Early Triassic sauropterygians, but the nature and rate of that elongation has not been documented. Here, we report a new species of pachypleurosaurid sauropterygian, Chusaurus xiangensis gen. et sp. nov., based on two new specimens from the Early Triassic Nanzhang-Yuan'an Fauna in the South China Block. The new species shows key features of its Middle Triassic relatives, but has a relatively short neck, measuring 0.48 of the trunk length, compared to > 0.8 from the Middle Triassic onwards. Comparative phylogenetic analysis shows that neck elongation occurred rapidly in all Triassic eosauropterygian lineages, probably driven by feeding pressure in a time of rapid re-establishment of new kinds of marine ecosystems.

First filter feeding in the Early Triassic: cranial morphological convergence between Hupehsuchus and baleen whales.

Modern baleen whales are unique as large-sized filter feeders, but their roles were replicated much earlier by diverse marine reptiles of the Mesozoic. Here, we investigate convergence in skull morphology between modern baleen whales and one of the earliest marine reptiles, the basal ichthyosauromorph Hupehsuchus nanchangensis, from the Early Triassic, a time of rapid recovery of life following profound mass extinction. Two new specimens reveal the skull morphology especially in dorsal view. The snout of Hupehsuchus is highly convergent with modern baleen whales, as shown in a morphometric analysis including 130 modern aquatic amniotes. Convergences in the snout include the unfused upper jaw, specialized intermediate space in the divided premaxilla and grooves around the labial margin. Hupehsuchus had enlarged its buccal cavity to enable efficient filter feeding and probably used soft tissues like baleen to expel the water from the oral cavity. Coordinated with the rigid trunk and pachyostotic ribs suggests low speeds of aquatic locomotion, Hupehsuchus probably employed continuous ram filter feeding as in extant bowhead and right whales. The Early Triassic palaeoenvironment of a restrictive lagoon with low productivity drove Hupehsuchus to feed on zooplankton, which facilitated ecosystem recovery in the Nanzhang-Yuan'an Fauna at the beginning of the Mesozoic.

Early Triassic marine reptile representing the oldest record of unusually small eyes in reptiles indicating non-visual prey detection.

The end-Permian mass extinction (EPME) led to reorganization of marine predatory communities, through introduction of air-breathing top predators, such as marine reptiles. We report two new specimens of one such marine reptile, Eretmorhipis carrolldongi, from the Lower Triassic of Hubei, China, revealing superficial convergence with the modern duckbilled platypus (Ornithorhynchus anatinus), a monotreme mammal. Apparent similarities include exceptionally small eyes relative to the body, snout ending with crura with a large internasal space, housing a bone reminiscent of os paradoxum, a mysterious bone of platypus, and external grooves along the crura. The specimens also have a rigid body with triangular bony blades protruding from the back. The small eyes likely played reduced roles during foraging in this animal, as with extant amniotes (group containing mammals and reptiles) with similarly small eyes. Mechanoreceptors on the bill of the animal were probably used for prey detection instead. The specimens represent the oldest record of amniotes with extremely reduced visual capacity, utilizing non-visual cues for prey detection. The discovery reveals that the ecological diversity of marine predators was already high in the late Early Triassic, and challenges the traditional view that the ecological diversification of marine reptiles was delayed following the EPME.

[Safety and efficiency of pacing at right ventricular outflow versus at ventricular cardiac apex].

OBJECTIVE: To compare the safety and efficiency of pacing at right ventricular outflow versus right ventricular apex. METHOD: Patients were divided into two groups: pacing at ventricular cardiac apex (common pacing group, n = 22) and pacing at right ventricular outflow tract (uncommon pacing group, n = 18). RESULTS: Impedance and amplitude of R-wave were similar during implantation between the two groups (all P > 0.05). The pacing threshold and electric current were significant higher in uncommon group than those in common pacing group (all P < 0.05), however, these differences disappeared at 1 month post pacemaker implantation (all P > 0.05). The mean QRS duration tended to be shorter in uncommon pacing group compared to that in common pacing group (P > 0.05). There was no pacemaker associated adverse effect in both groups. CONCLUSION: The safety and efficiency of pacing at right ventricular outflow was similar as those of pacing at right ventricular apex.

[Report on initiating clinical research for electrical and mechanical synchronism of selective region pacing in the right ventricular].

OBJECTIVE: To verify the electric synchronism, mechanic synchronism and hemodynamics of selective site pacing. METHODS: Pacing in the right ventricular cardiac apex (RVA), the right ventricular His bundle region (His), and the septum of right ventricular high-positioned outflow tract (RVOT), CO and CI were recorded. The electrical synchronism was assessed by observing the width and shape in a 12-lead surface ECG. The mechanical synchronism was estimated by using the VVI (vector velocity imaging) technology of the Acuson Sequia 512. RESULTS: The results showed that CO and CI were lower while pacing in RVA, but they were not significant different (P>0.05). The QRS width: (124 +/- 5.3) ms while pacing in His, (144 +/- 7.1) ms while pacing in RVOT and (156 +/- 8.6) ms while pacing in RVA. The QRS width while pacing in His and in RVOT were narrower than in RVA and there were significant differences (P<0.01). Vector velocity imaging showed that mechanical synchronism was better while pacing in RVOT than that in RVA. CONCLUSION: Pacing in RVOT seems better than pacing in traditional RVA, and the operation was no more difficult than the traditional operation.