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The role of paleontological data in testing homology by congruence

100%
Rieppel O.
Acta Palaeontologica Polonica
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1993
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tom 38
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nr 3-4
295-302
With homology being defined as shared similarity due to common ancestry, any initial perception of similarity (or relative invariance) among organisms may be treated as a conjecture of homology to be tested by congruence. The phylogenetic information content is therefore not with the character itself, but lies in the relation of any one character to all others known. The "principle of total evidence" thus emerges as a logical corollary of the distinction of homology and homoplasy, the most severe test of homology involving all known characters in the search for the globally most congruent pattern. In a study combining fossil and extant organisms, however, the issue of missing characters raises the question of implicit a priori weighting, because some sources for characters (soft anatomy, molecular, physiological, behavioral) remain unknown in fossils. The issue of missing data in fossils requires further study before the potential impact of fossils on a classification based on extant organisms can be properly assessed.
2
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The first Triassic vertebrate fossils from Myanmar: Pachypleurosaurs in a marine limestone

45%
San K. K., Fraser N. C., Foffa D., Rieppel O., Brusatte S. L.
Acta Palaeontologica Polonica
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2019
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tom 64
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nr 2
As ecosystems recovered from the end-Permian extinction, many new animal groups proliferated in the ensuing Triassic. Among these were the sauropterygians, reptiles that evolved from terrestrial ancestors and transitioned to a marine environment. The first sauropterygians were small, marine-adapted taxa such as pachypleurosaurs, which are known from Middle–Late Triassic deposits, particularly in the Tethyan realm of Europe, and more recently from Lagerstätten in southwestern China. Here we report two pachypleurosaurs from Myanmar, the first Triassic vertebrate fossils from the country. These specimens demonstrate that their entombing rocks in northern Shan State, which have received less study than terrestrial sediments in southern Shan State and whose ages have long been uncertain, are Triassic. The specimens may be among the oldest pachypleurosaurs globally, potentially corroborating biogeographic scenarios that posit an eastern Tethyan origin for pachypleurosaurs, and raise the potential for future discoveries of well-preserved Triassic reptiles in Myanmar.
3
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New information on sexual dimorphism and allometric growth in Keichousaurus hui, a pachypleurosaur from the Middle Triassic of Guizhou, South China

33%
Xue Y., Jiang D., Motani R., Rieppel O., Sun Y., Sun Z., Ji C., Yang P.
Acta Palaeontologica Polonica
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2015
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tom 60
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nr 3
Keichousaurus hui is a small pachypleurosaur (Reptilia: Sauropterygia) from the Triassic of China. Many specimens of various growth stages are known, making them ideal for ontogenetic research. We report 22 new specimens from the Middle Triassic of Xingyi (Guizhou, south China), and combined their skeletal measurements with those from 85 published specimens to analyze the ontogenetic trajectory of sexual dimorphism. An Exploratory Factor Analysis suggests that the largest factors behind morphological disparity within the species are body size followed by gender. Sexual dimorphism is most clearly reflected in selected skeletal ratios that are more pronounced in males than in females. We found that the relative length of femur to body size was useful in gender identification, in addition to three ratios that are traditionally used, namely a distal expansion of the humerus relative to its shaft, humerus length relative to body size, and humerus length relative to femur length. Two distinctive patterns exist in allometric changes of these four ratios. The distal expansion of the humerus is exceptional in that it is equally pronounced in juvenile and adult males and therefore must have been fully established during embryonic growth. The other three features are not pronounced at birth size and subsequently become pronounced during postembryonic growth. However, males and females already show different growth trajectories at birth size even in these three. Therefore, the fate of sexually dimorphic features seems to have already been set during embryonic growth in K. hui.
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