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Larval development in Oligocene palaeobatrachid frogs

100%

Rocek Z.

Acta Palaeontologica Polonica

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2003

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tom 48

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nr 4

A detailed account of the development of skeletal and some soft−tissue structures is based on 171 fossil tadpoles and metamorphosing froglets of Palaeobatrachus sp. from the Late Oligocene of the Czech Republic (locality Bechlejovice). Their exceptionally good preservation resulted from fossilization in diatomites. The fossil developmental series was compared with normal development of the contemporary anuran Xenopus laevis (Pipidae) represented by cleared and stained (alizarin/toluidin−blue) whole−mount specimens. The comparison revealed that in spite of differences in the sequence of ossification and its timing (e.g., ossification of the otic capsules and ribs was retarded in Xenopus whereas dermal ossification was retarded in Palaeobatrachus), in the number of free ribs, and in composition of the sacral region (the synsacrum in Palaeobatrachus involves two posterior presacrals, whereas there is a single sacral in Xenopus), both genera were similar in great number of anatomical features that appear during development. The most important difference is the shape of vertebral centrum (procoelous in Palaeobatrachus, opisthocoelous in all Pipidae) which is formed in comparatively early developmental stages. A view that could result from anatomical comparisons is that Palaeobatrachus could be derived from the Pipidae, but this is doubtful due to biostratigraphic and palaeogeographic discrepancies. The earliest palaeobatrachids were recorded from the Late Cretaceous of Europe but pipids could not invade northern continents after the Early Cretaceous when the Tethys Sea prevented interchanges of anuran faunas. Also, all palaeobatrachids retain primitive anatomical features (e.g., five pairs of ribs) that were more derived even in the earliest pipids from the Lower Cretaceous of Israel.

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List of fossil amphibians of Czechoslovakia

88%

Rocek Z.

Acta Zoologica Cracoviensia

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1988

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tom 31

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nr 2 (11-27)

3

Patterns of larval development in Cretaceous pipid frogs

63%

Rocek Z., Van Dijk E.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 1

A developmental series of nearly 250 tadpoles of Shomronella jordanica from the Early Cretaceous (Hauterivian) of the Shomron (Samaria) region of central Israel, a small collection (12) of Thoraciliacus rostriceps tadpoles from the Early Cretaceous (Aptian) of Makhtesh Ramon, Israel, and 13 tadpoles from the Late Cretaceous (Campanian/Maastrichtian boundary) of Stompoor, Marydale, South Africa were studied. These were compared with published data on the development of Paleogene (Middle Eocene–Early Oligocene) pipids from Patagonia, and with normal development of the contemporary pipid frog Xenopus. The comparisons of the developmental series of the Cretaceous and contemporary pipid frogs provided data on changes in the developmental pattern, namely of the degree of ossification and other developmental events. In general, it seems that ossification has become considerably delayed in the course of pipid evolution, whereas most anatomical features typical for free living pipid larvae were well established as early as in the Early Cretaceous. Comparisons with the developmental series of specimens from the Late Oligocene Palaeobatrachidae (closely related to the Pipidae) from Bechlejovice near Děčín, Czech Republic revealed that some morphological differences between the two families might be explained by their developmental mode (e.g., formation of the opisthocoelous vertebral centrum in Shomronella). The uncinate process on three anterior pairs of ribs in Shomronella is the character retained in primitive anurans, and indicates close phylogenetic relations of early pipoids to discoglossoids.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Acta Zoologica Cracoviensia

3 Rocek Z.

1 Van Dijk E.

1 2006

1 2003

1 1988

Larval development in Oligocene palaeobatrachid frogs

List of fossil amphibians of Czechoslovakia

Patterns of larval development in Cretaceous pipid frogs