Richard A. Kissel

Bio: Richard A. Kissel is an academic researcher from University of Toronto. The author has contributed to research in topics: Diadectomorpha & Permian. The author has an hindex of 4, co-authored 4 publications receiving 129 citations.

A new diadectid (diadectomorpha), orobates pabsti, from the early permian of central germany

Abstract: A new genus and species of the herbivorous Diadectidae, Orobates pabsti, is described on the basis of several specimens, including two complete, articulated skeletons, a skull with partial postcranium, a partial skull, and a dentigerous jaw fragment. All were collected from the Lower Permian (Wolfcampian) Tambach Formation, lowermost formational unit of the Upper Rotliegend of the Bromacker quarry locality in the midregion of the Thuringian Forest near Gotha, central Germany. A combination of autapomorphic and plesiomorphic character states clearly distinguishes O. pabsti from all other well-known members of Diadectidae and identifies it as the sister taxon to all other diadectids. The description of Orobates pabsti expands further our understanding of the Late Pennsylvanian-Early Permian Diadectidae and records the earliest specialization of tetrapods to high-fiber herbivory. On the basis of paleobiological and paleoenvironmental data only one other Early Permian locality is comparable to the Br...

Captorhinus magnus, a new captorhinid (Amniota: Eureptilia) from the Lower Permian of Oklahoma, with new evidence on the homology of the astragalus

Abstract: The new species of single tooth-rowed captorhinid reptile Captorhinus magnus n. sp. from the Lower Permian fissure fillings at Richards Spur, Oklahoma differs from Captorhinus aguti in body size an...

Upper pennsylvanian tetrapods from the ada formation of seminole county, oklahoma

Abstract: A recently discovered tetrapod-bearing locality (OMNH V1005) in the Upper Pennsylvanian Ada Formation of Oklahoma has produced the remains of six taxa: the pelycosaurian-grade synapsid Ophiacodon cf. mirus, an indeterminate sphenacodontian pelycosaur, the temnospondyl Eryops? sp., the rare diadectid Diasparactus zenos, and two unidentified taxa known only from jaw fragments. The skeletal material comprises an allochthonous assemblage transported by low-velocity currents prior to burial. Except for four articulated Ophiacodon vertebral segments, all fossil material recovered in situ was disarticulated. The bones were not exposed to prolonged periods of weathering prior to burial. OMNH V1005 records the first occurrence of Eryops, Diasparactus, and Ophiacodon from the Pennsylvanian of Oklahoma. The presence of Diasparactus zenos indicates that this species was not endemic to New Mexico, as formerly believed. An associated dentary provides the first well-preserved cheek teeth of Diasparactus zenos. ...

Taphonomic and Ecologic Information Form Bone Weathering

Abstract: Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

The Osteology of the Reptiles

Abstract: IN no domain of zoological science have the con tributions of American naturalists been more splendid than in that of vertebrate palaeontology, and in the list of pioneer workers in this domain an honoured place will always be accorded to Samuel Wendell Williston, who, born and nurtured in obscurity, had by the time of his death in 1918 won his way to recogni tion as the chief authority upon the extinct amphibians and reptiles. Apart from his specialist papers upon fossil vertebrates and upon modern dipterous flies, Williston was well known to the general zoologist for his excellent book on “Water Reptiles of the Past and Present,” published in 1914, and during the last year of his life he was busily engaged in the preparation of a second work of a general character on “The Reptiles of the World, Recent and Fossil.” The volume now under review comprises the main part of this general work, so far as it had been completed at the time of the author's death, put into shape and edited at the competent hands of Prof. W. K. Gregory. The Osteology of the Reptiles. By Prof. Samuel Wendell Williston. Arranged and edited by Prof. William King Gregory. Pp. xiii + 300. (Cambridge, Mass.: Harvard University Press; London: Oxford University Press, 1925.) 18s. 6d. net.

Dates, nodes and character conflict: addressing the Lissamphibian origin problem

Abstract: Synopsis Extant amphibians consist of Salientia (frogs), Caudata (salamanders), and Gymnophiona (caecilians). The mutual relationships of these groups are controversial, with either Batrachia (Salientia + Caudata) or Procera (Gymnophiona + Caudata) as emerging clades in recent molecular and morphological analyses. The monophyly of amphibians as a whole is supported by independent data, but their origins and affinities with early tetrapods are debated. A new cladistic analysis of early tetrapods retrieves Temnospondyli (the most species‐rich group of early tetrapods) as the closest relatives of crown group amphibians. One temnospondyl group, the Dissorophoidea, forms a series of consecutive outgroups to crown amphibians. In particular, the Lower Permian amphibamid Doleserpeton is the most derived plesion on the amphibian stem. The Albanerpetontidae, a group of salamander‐like tetrapods ranging from the Jurassic to the Pliocene, are placed as stem Gymnophiona. The shortest trees support the Batrachia hypoth...

Reverse-engineering the locomotion of a stem amniote

Abstract: Reconstructing the locomotion of extinct vertebrates offers insights into their palaeobiology and helps to conceptualize major transitions in vertebrate evolution1–4. However, estimating the locomotor behaviour of a fossil species remains a challenge because of the limited information preserved and the lack of a direct correspondence between form and function5,6. The evolution of advanced locomotion on land—that is, locomotion that is more erect, balanced and mechanically power-saving than is assumed of anamniote early tetrapods—has previously been linked to the terrestrialization and diversification of amniote lineages7. To our knowledge, no reconstructions of the locomotor characteristics of stem amniotes based on multiple quantitative methods have previously been attempted: previous methods have relied on anatomical features alone, ambiguous locomotor information preserved in ichnofossils or unspecific modelling of locomotor dynamics. Here we quantitatively examine plausible gaits of the stem amniote Orobates pabsti, a species that is known from a complete body fossil preserved in association with trackways8. We reconstruct likely gaits that match the footprints, and investigate whether Orobates exhibited locomotor characteristics that have previously been linked to the diversification of crown amniotes. Our integrative methodology uses constraints derived from biomechanically relevant metrics, which also apply to extant tetrapods. The framework uses in vivo assessment of locomotor mechanics in four extant species to guide an anatomically informed kinematic simulation of Orobates, as well as dynamic simulations and robotics to filter the parameter space for plausible gaits. The approach was validated using two extant species that have different morphologies, gaits and footprints. Our metrics indicate that Orobates exhibited more advanced locomotion than has previously been assumed for earlier tetrapods7,9, which suggests that advanced terrestrial locomotion preceded the diversification of crown amniotes. We provide an accompanying website for the exploration of the filters that constrain our simulations, which will allow revision of our approach using new data, assumptions or methods. Quantitative explorations using biomechanics and robotics of the gait of Orobates, a stem amniote, indicate that the development of relatively erect, power-saving and balanced locomotion preceded the diversification of crown amniotes

Evolution of humeral microanatomy and lifestyle in amniotes, and some comments on palaeobiological inferences

Abstract: A study on the most exhaustive taxonomic sample of amniotes (75 extant and nine extinct taxa) of any quantitative work on this topic published so far demonstrates a strong relationship between lifestyle (aquatic, amphibious or terrestrial) and humeral microanatomy. We suggest that corrections for multiple testing be used to check for statistical artefacts in the context of a phylogenetic independent contrast analysis, and we use the false discovery rate procedure for this. Linear discriminant models segregate the various lifestyles with excellent success rate of up to 98.5%. Lifestyle was thus inferred for six extinct taxa of uncertain habitat. The results obtained suggest that Captorhinus, Claudiosaurus, and Placodus were amphibious, whereas Neusticosaurus and Mesosaurus were aquatic. Lystrosaurus may have been more aquatic than previously suggested, although the results of our inference models have to be integrated with other sources of data, which suggest that it may have been amphibious, rather than aquatic (as a literal interpretation of the models would suggest). Finally, we propose an alternative method of palaeobiological inference for hypothetical ancestors. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 384–406.