ventastega skeleton

Ventastega curonica

Until the recent studies of Acanthostega, specimens of Ventastega curonica languished in a museum drawer as an "unidentified sarcopterygian". Now, known as a tetrapod, it's one of the more complete of the Late Devonian tetrapods. Much of the skull, including the palete, and lower jaw is known. These elements generally resemble those of Acanthostega. However, some features of its lower jaw suggest that Ventastega may be less derived.

The post-cranial skeleton of Ventastega, however, is much less complete. Elements include the clavicle (collarbone), the upper shoulder (primarily the cleithrum), a radius (forearm), part of the pelvis, and assorted ribs and tail fin rays.

Ventastega was revovered from what are probably stream-influenced near-shore marine sediments of the Ketleri Formation (upper Famennian, Late Devonian) in Latvia. Most fossils at this locality occur as disarticulated but well-preserved elements, suggesting that postmortem transport was limited. The associated vertebrates remains were dominated by an antiarch placoderm, Bothriolepis ciecere. Other vertebrates include acanthodians, an unidentified rayfin, a lungfish (Orlovichthys sp.), two porolepiform lobe-fins (Holoptychius sp. and Ventalepis ketlereiensis) and two osteolepiform lobe-fins (Cryptolepis grossi and Glyptopomus sp.).

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G.R. Morton's Transitional Forms: Fish to Amphibian:
Clack, J.A. 2002. Gaining Ground: The Origin and Early Evolution of Tetrapods. Bloomington: Indiana Univ. Press.
Janvier, P. 1996. Early Vertebrates. Oxford: Claredon Press.
Scientific Papers
Ahlberg, P.E., E. Luksevicks, and O.A. Lebedev. 1994. "The first tetrapod finds from the Devonian (Upper Famennian) of Latvia." Philos. Trans. R. Soc. London B. 343: 303-328.
Ahlberg, P.E. and E. Luksevics. 2004. "New Light on the Devonian tetrapod Ventastega curonica." (abstract) 10th International Symposium on Early Vertebrates/Lower Vertebrates. Gramado, Brazil. 2004 May.
Ahlberg, P.E., E. Luksevics and O. Levedev. 1994. "The first tetrapod finds from the Devonian (Upper Famennian) of Latvia." Philosophical Transactions of the Royal Society of London, Series B. 343: 303-328.
Clack, J.A. 1997. "Devonian tetrapod trackways and trackmakers: a review of the fossils and footprints." Paleogeography, Paleoclimatology, Paleoecology 130: 227-250.
Luksevics, E. and I. Zupins. 2004. "Sedimentology, fauna, and taphonomy of the Pavari site, Late devonian of Latvia." Acta Universitatis Tatviensis 679: 99-119.

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