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New lizards and rhynchocephalians from the Lower Cretaceous of Southern Italy

100%

Evans S. E., Raia P., Barbera C.

Acta Palaeontologica Polonica

2004

tom 49

nr 3

The Lower Cretaceous (Albian age) locality of Pietraroia, near Benevento in southern Italy, has yielded a diverse assemblage of fossil vertebrates, including at least one genus of rhynchocephalian (Derasmosaurus) and two named lizards (Costasaurus and Chometokadmon), as well as the exquisitely preserved small dinosaur, Scipionyx. Here we describe material pertaining to a new species of the fossil lizard genus Eichstaettisaurus (E. gouldi sp. nov.). Eichstaettisaurus was first recorded from the Upper Jurassic (Tithonian age) Solnhofen Limestones of Germany, and more recently from the basal Cretaceous (Berriasian) of Montsec, Spain. The new Italian specimen provides a significant extension to the temporal range of Eichstaettisaurus while supporting the hypothesis that the Pietraroia assemblage may represent a relictual island fauna. The postcranial morphology of the new eichstaettisaur suggests it was predominantly ground−living. Further skull material of E. gouldi sp. nov. was identified within the abdominal cavity of a second new lepidosaurian skeleton from the same locality. This second partial skeleton is almost certainly rhynchocephalian, based primarily on foot and pelvic structure, but it is not Derasmosaurus and cannot be accommodated within any known genus due to the unusual morphology of the tail vertebrae.

Fractal analysis of ostracod shell variability: A comparison with geometric and classic morphometrics

76%

Aiello G., Barattolo F., Barra D., Fiorito G., Mazzarella A., Raia P., Viola R.

Acta Palaeontologica Polonica

2007

tom 52

nr 3

Two statistical methods, fractal geometry and geometric morphometrics, are tested for their applicability to ostracod systematics. For this comparison, two morphologically similar ostracod species (Krithe compressa and Krithe iniqua) whose genus−level systematics is still incompletely resolved, are selected. Twenty−nine right valves of each species were collected from the upper Pliocene samples at the Monte San Nicola section in southern Italy. Statistical analyses (MANOVA on morphometric shape variables, and D values) were utilized to test if geometric morphometrics and fractal analysis are appropriate into discriminating between the two species. Both methods succeeded in distinguishing the species statistically. The fractal analysis of the two ostracod species shows D values centered on 1.31±0.02 for Krithe iniqua and on 1.40±0.02 for Krithe compressa. Geometric morphometric analysis indicates significant differences between the two species and allows studying intra−populational variability as well as. The most variable traits indicated by geometric morphometrics are vestibular area and posterior outline of the shell, indicating that these traits are the most relevant for the systematics of the species analyzed. Both fractal geometry and geometric morphometrics provide a measure of population variability. Fractal analysis has the advantage of being free from any subjectivity in the selection of characters and could be most appropriate to use for analysis of complex ornamentation for systematic purposes. However, a possible advantage of geometric morphometrics over fractal analysis is its ability to indicate where statistically significant variations in shape occur on the shell.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

2 Raia P.

1 Aiello G.

1 Barattolo F.

1 Barbera C.

1 Barra D.

1 Evans S. E.

1 Fiorito G.

1 Mazzarella A.

1 Viola R.

1 2007

1 2004

Wyniki wyszukiwania

New lizards and rhynchocephalians from the Lower Cretaceous of Southern Italy

Fractal analysis of ostracod shell variability: A comparison with geometric and classic morphometrics