Jason D. Pardo

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 The adriamycin-induced rat model of the VATER association has provided a means of studying the morphogenesis of a variety of major congenital structural abnormalities similar to those seen in humans with the VATER association. Most interest has been centered on the foregut, where the model has clarified some aspects of the development of esophageal atresia(More)
Recumbirostran 'microsaurs,' a group of early tetrapods from the Late Carboniferous and Early Permian, are the earliest known example of adaptation to head-first burrowing in the tetrapod fossil record. However, understanding of the diversity of fossorial adaptation within the Recumbirostra has been hindered by poor anatomical knowledge of the more(More)
The Early Permian recumbirostran lepospondyl Rhynchonkos stovalli has been identified as a possible close relative of caecilians due to general similarities in skull shape as well as similar robustness of the braincase, a hypothesis that implies the polyphyly of extant lissamphibians. In order to better assess this phylogenetic hypothesis, we studied the(More)
Complete, exceptionally-preserved skulls of the Permian lungfish Persephonichthys chthonica gen. et sp. nov. are described. Persephonichthys chthonica is unique among post-Devonian lungfishes in preserving portions of the neurocranium, permitting description of the braincase of a stem-ceratodontiform for the first time. The completeness of P. chthonica(More)
Christensen et al. recently published a study of hearing in neotenic and experimentally metamorphosed axolotls (Ambystoma mexicanum) and a larval and adult tiger salamander (A. tigrinum), which contributes greatly to our understanding of salamander sound perception in water and air [1]. They demonstrate that premetamorphic, atympanic aquatic salamanders are(More)
Phylogenetic analysis of early tetrapod evolution has resulted in a consensus across diverse data sets in which the tetrapod stem group is a relatively homogenous collection of medium- to large-sized animals showing a progressive loss of 'fish' characters as they become increasingly terrestrial, whereas the crown group demonstrates marked morphological(More)
Polyglactin and nylon suture material were compared in microsurgical anastomosis of oviduct of rabbits with regard to the histologic reaction, adhesion formation, and nidation index. Thirty days after surgery, the tissue inflammatory response was very similar in both groups. At 90 days, polyglactin had been totally absorbed in 80% of the cases, and no(More)
Lysorophians are a group of early tetrapods with extremely elongate trunks, reduced limbs, and highly reduced skulls. Since the first discovery of this group, general similarities in outward appearance between lysorophians and some modern lissamphibian orders (specifically Urodela and Gymnophiona) have been recognized, and sometimes been the basis for(More)
The origin of the limbless caecilians remains a lasting question in vertebrate evolution. Molecular phylogenies and morphology support that caecilians are the sister taxon of batrachians (frogs and salamanders), from which they diverged no later than the early Permian. Although recent efforts have discovered new, early members of the batrachian lineage, the(More)