On a fossil lobster (Decapoda, Malacostraca, Crustacea) from the Riachuelo Formation, Albian of the Sergipe Basin, Brazil

ON A FOSSIL LOBSTER (DECAPODA, MALACOSTRACA, CRUSTACEA) FROM THE RIACHUELO FORMATION, ALBIAN OF THE SERGIPE BASIN, BRAZIL

CAIO V.G. TURBAY ¹; PEDRO CESERO ¹AND EDUARDO A. KOUTSOUKOS ²

¹ Departamento de Paleontologia e Estratigrafia, UERJ.

² PETROBRAS / CENPES.

Presented by DIOGENES DE ALMEIDA CAMPOS

The occurrence of a fossil lobster in a sandstone layer of the Riachuelo Formation (Albian), Sergipe Basin is recorded here. The fossil was collected nearby Laranjeiras city, in the Brejo Quarry (UTM coordinates: 0701754; 8807678), Riachuelo Formation, Sergipe Basin. Biostratigraphic studies show that the quarry lies within the Mortoniceras biozone, of Late Albian age. The Riachuelo Formation represents the open marine stage of the drifting process and is formed by high-energy shelf carbonate deposits (oncolitic-oolitic-peloidal-bioclastic packstones and grainstones), interbedded with lagoonal mudstones and siltstones, and fan-delta like siliciclastic rocks. The fossil was found in a fine-grained sandstone layer of the Angico Member, which is very exposed in the uppermost section of the Brejo Quarry. The main outcrop comprises three shallowing-upward carbonate cycles, overlain by siliciclastic storm layers with microhummocky structures. The studied specimen is badly preserved showing only the quitinous skeleton that was fossilized by carbonization as denoted by its thin and very fragile surface. Five abdominal segments and the cephalothorax as well as the rostrum are exposed. The sedimentary facies of the Brejo Quarry is characteristic of a shallow carbonate shelf environment with sandy barriers generated under high-to-moderate energy conditions. A restricted lagoon was formed backwards to the carbonate shelf. Siliciclastic sediments filled in the platform as a result of gravitational flows from the basin borders. This fossil lobster probably lived in the muddy bottom of a lagoonal environment near the fan-delta systems, and was subsequently reworked by storms and preserved in the sandstone layer where it was recovered. — ( December 20, 2001 ).

Publication Dates

• Publication in this collection
  17 July 2002
• Date of issue
  June 2002