A relict stem salamander: Evidence from the Early Cretaceous of Siberia

The early evolution of salamanders, which are one of the three living groups of lissamphibians, is not well known. Both stem- and crown-group salamanders first appeared in the Middle Jurassic (Bathonian), but subsequently had different evolutionary histories: stem salamanders were thought to have gone extinct in the Late Jurassic, while crown salamanders persist to the present day. Here, I report the discovery of an indeterminate stem salamander in the Lower Cretaceous (Aptian–Albian) Ilek Formation of Western Siberia. This is new evidence that the most basal salamanders survived beyond the Jurassic–Cretaceous boundary and co-existed with crown-group salamanders during approximately the first 40 million years of the known history of salamanders. The recognition of stem salamanders in the Early Cretaceous of Western Siberia adds to the inventory of taxa that suggest this area was a refugium for various groups of vertebrates with Jurassic affinities

On a record of Choristoderes (Diapsida, Choristodera) from the Lower Cretaceous of Western Siberia

Fossil remains (fragmentary dentaries and vertebrae) of Choristodera indet. from the Lower Cretaceous Shestakovo 1 locality (Kemerovo Region, Russia) are described. The taxon from Shestakovo is characterized by primitive vertebral features (fused neural arches and centra of the cervical vertebrae, elongated dorsal vertebrae) combined with the presence of dentin folds at the tooth bases (advanced character typical of neochoristoderes). Phylogenetic relationships of the form from Shestakovo and other Choristodera are uncertain

A relict stem salamander: Evidence from the Early Cretaceous of Siberia

The early evolution of salamanders, which are one of the three living groups of lissamphibians, is not well known. Both stem- and crown-group salamanders first appeared in the Middle Jurassic (Bathonian), but subsequently had different evolutionary histories: stem salamanders were thought to have gone extinct in the Late Jurassic, while crown salamanders persist to the present day. Here, I report the discovery of an indeterminate stem salamander in the Lower Cretaceous (Aptian–Albian) Ilek Formation of Western Siberia. This is new evidence that the most basal salamanders survived beyond the Jurassic–Cretaceous boundary and co-existed with crown-group salamanders during approximately the first 40 million years of the known history of salamanders. The recognition of stem salamanders in the Early Cretaceous of Western Siberia adds to the inventory of taxa that suggest this area was a refugium for various groups of vertebrates with Jurassic affinities

Une salamandre géante « préglaciaire » d’Europe : nouveau signalement du Pliocène supérieur du Caucase

Des os crâniens et post-crâniens désarticulés d’une salamandre géante (Cryptobranchidae : Andrias sp.) ont été trouvés dans les dépôts du Pliocène supérieur de la localité de Belorechensk dans le Caucase du Nord. Ces restes appartenaient probablement à un individu décédé au cours de la phase de croissance rapide et d’une longueur totale d’environ 90 à 100 cm. La salamandre géante de Belorechensk est l’une des plus récentes et des plus connues d’Europe.Disarticulated cranial and postcranial bones of a giant salamander (Cryptobranchidae: Andrias sp.) were found in the Upper Pliocene deposits of the Belorechensk locality in the Northern Caucasus. These remains probably belonged to one individual that died during a stage of rapid growth and had a total length of about 90-100 cm. The giant salamander from Belorechensk is among the geologically youngest and the easternmost known in Europe.</p

Early Cretaceous choristoderes (Diapsida, Choristodera) from Siberia, Russia

There are ten known Lower Cretaceous localities for skeletal remains of choristoderes in Siberia (Russia). Choristoderan remains at all these localities are represented by isolated bones, usually by isolated vertebrae of Choristodera indet. Three choristoderan taxa in two geological units were identified: the non-neochoristodere Khurendukhosaurus sp. (possibly closely related to the long-necked Sino-Japanese hyphalosaurids) from the Murtoi Formation, Transbaikalia; cf. Khurendukhosaurus sp. and the “Shestakovo choristodere” with possible neochoristoderan affinities from the Ilek Formation, Western Siberia. All these three choristoderan taxa had a microanatomical organization of vertebrae similar to that of in advanced large neochoristoderes (vertebral centra with tight spongiosa). The Siberian fossil record includes the westernmost (Shestakovo locality, Ilek Formation) and the northernmost (Teete locality, the Sangarian Group) occurrences of the Early Cretaceous choristoderes in Asia. Like in other regions of Asia, Siberian localities are characterized by the absence of neosuchian crocodyliforms

On a record of Choristoderes (Diapsida, Choristodera) from the Lower Cretaceous of Western Siberia

Fossil remains (fragmentary dentaries and vertebrae) of Choristodera indet. from the Lower Cretaceous Shestakovo 1 locality (Kemerovo Region, Russia) are described. The taxon from Shestakovo is characterized by primitive vertebral features (fused neural arches and centra of the cervical vertebrae, elongated dorsal vertebrae) combined with the presence of dentin folds at the tooth bases (advanced character typical of neochoristoderes). Phylogenetic relationships of the form from Shestakovo and other Choristodera are uncertain