Acanthoceras jukesbrownei Zone: Difference between revisions
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'''Base''': The base of the zone is immediately below the first appearance of the index species (Robaszynski ''et al''., 1998). | '''Base''': The base of the zone is immediately below the first appearance of the index species (Robaszynski ''et al''., 1998). | ||
'''Top''': The top of the zone is immediately above the last occurrence of the index species (Robaszynski ''et al''., 1998). | '''Top''': The top of the zone is immediately above the last occurrence of the index species (Robaszynski ''et al''., 1998). | ||
'''Range of index species''': The zone is coincident with the total range of the index species (Robaszynski ''et al''., 1998). | '''Range of index species''': The zone is coincident with the total range of the index species (Robaszynski ''et al''., 1998). | ||
'''Key fauna:''' | '''Key fauna:''' | ||
{| class="Wikitable" | |||
| Bivalvia: || ''Inoceramus atlanticus'' | |||
Bivalvia: | |- | ||
| ||'' I. pictus'' | |||
|- | |||
| ||''Pycnodonte vesiculare'' (locally abundant) | |||
'' I. pictus'' | |- | ||
| Ammonoidea:|| ''Acanthoceras jukesbrownei'' | |||
|} | |||
''Pycnodonte vesiculare'' (locally abundant) | |||
Ammonoidea: ''Acanthoceras jukesbrownei'' | |||
'''Faunal abundance & preservation''': ''Pycnodonte'' and ''Inoceramus'' are locally very abundant (see Bio-markers). ''Acanthoceras'' tends to be rather poorly preserved as iron-stained chalky moulds. | '''Faunal abundance & preservation''': ''Pycnodonte'' and ''Inoceramus'' are locally very abundant (see Bio-markers). ''Acanthoceras'' tends to be rather poorly preserved as iron-stained chalky moulds. | ||
'''Bio-markers''': ''Inoceramus atlanticus'' is abundant in the base of the ''jukesbrownei'' Zone (Gale, 1995). A marl in the lower part of the zone contains abundant ''Pycnodonte'' ''vesiculare'', and represents the basal part of Jukes-Browne Bed 7. This marl marks the change from ''Inoceramus atlanticus'' below to ''Inoceramus pictus'' above, both species locally occurring in the marl. | '''Bio-markers''': ''Inoceramus atlanticus'' is abundant in the base of the ''jukesbrownei'' Zone (Gale, 1995). A marl in the lower part of the zone contains abundant ''Pycnodonte'' ''vesiculare'', and represents the basal part of Jukes-Browne Bed 7. This marl marks the change from ''Inoceramus atlanticus'' below to ''Inoceramus pictus'' above, both species locally occurring in the marl. | ||
'''Age''': Mid Cenomanian | '''Age''': Mid Cenomanian | ||
Latest revision as of 12:53, 26 September 2013
Base: The base of the zone is immediately below the first appearance of the index species (Robaszynski et al., 1998).
Top: The top of the zone is immediately above the last occurrence of the index species (Robaszynski et al., 1998).
Range of index species: The zone is coincident with the total range of the index species (Robaszynski et al., 1998).
Key fauna:
| Bivalvia: | Inoceramus atlanticus |
| I. pictus | |
| Pycnodonte vesiculare (locally abundant) | |
| Ammonoidea: | Acanthoceras jukesbrownei |
Faunal abundance & preservation: Pycnodonte and Inoceramus are locally very abundant (see Bio-markers). Acanthoceras tends to be rather poorly preserved as iron-stained chalky moulds.
Bio-markers: Inoceramus atlanticus is abundant in the base of the jukesbrownei Zone (Gale, 1995). A marl in the lower part of the zone contains abundant Pycnodonte vesiculare, and represents the basal part of Jukes-Browne Bed 7. This marl marks the change from Inoceramus atlanticus below to Inoceramus pictus above, both species locally occurring in the marl.
Age: Mid Cenomanian