- Source: Watinoceras
Watinoceras is a genus of acanthoceratid ammonite that lived during the early Turonian stage of the Late Cretaceous.
Description
Early whorls are compressed, finely ribbed with inner and outer ventrolateral and siphonal tubercles as in Neocardioceras, but siphonal row is soon lost. Later the venter may be concave between rows of ventrolateral clavi or rounded with ribs passing over in chevrons. Ornament usually becomes coarser with age. Derivation is from Neocardioceras, Watinoceras and Mammites gave rise to the other genera in the subfamily Acanthoceratinae. Older classifications included Watinoceras in the subfamily Mammitinae instead.
Species include W. coloradoense, W. reesidei, and W. thompsonense.
Biostratigraphic significance
The first occurrence of the species Watinoceras devonense marks the beginning of the Turonian.
Distribution
Fossils of the genus have been found in:
Ponta das Salinas, Angola
Cotinguiba Formation, Brazil
Mungo River Formation, Cameroon
Blackstone Formation, Alberta, Canada
Second White Speckled Shale and Kaskapu Formations, British Columbia
McKenzie River Valley, Pacific Northwest
Mesitas del Colegio and Yaguará, Colombia
Brießnitz Formation, Germany
Agua Nueva and Indidura Formations, Mexico
Eze-Aku Formation, Nigeria
Draa el Miaad, Tunisia
Mancos Shale, Arizona and New Mexico
Greenhorn Formation, Colorado and Minnesota
Colorado Group, Colorado and New Mexico
La Luna Formation, Venezuela
References
Further reading
W.J. Arkell et al., 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Pat L Mollusca 4. Geological Society of America and University of Kansas Press.
J. Kennedy et al., 1999. Lower Turonian (Upper Cretaceous) Watinoceras devonense Zone ammonite fauna in Colorado, USA. USGS Publications Warehouse - Citations View