''Nipponites'' is an extinct
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
heteromorph
The Ancyloceratina were a diverse suborder of ammonite most closely related to the ammonites of order Lytoceratina. They evolved during the Late Jurassic but were not very common until the Cretaceous period, when they rapidly diversified and bec ...
ammonite
Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...
s. The shells of ''Nipponites'' (primarily ''N. mirabilis'') form "ox-bow" bends, resulting in some of the most bizarre shapes seen among ammonites.
The ecology of ''Nipponites'', as with many other
nostoceratids, is subject to much speculation.
Distribution
Fossils of most species are found primarily in
Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
strata of Japan. ''N. mirabilis'' is found in
Coniacian
The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...
-aged strata of Japan and possibly
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by t ...
-aged strata in Madagascar.
''N. bacchus'' is found in Upper Cretaceous Hokkaido. Two species are found exclusively outside Japan, ''N. sachalinensis'', which is found in Upper Cretaceous strata of Sakhalin island, and Kamchatka peninsula,
[Shigeta, Yasunari, and Haruyoshi Maeda. "Yezo Group research in Sakhalin—a historical review." National Science Museum Monographs 31 (2005): 1-24.] and ''N. occidentalis'', which is known from two shells found in the
Turonian
The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded by t ...
-aged Hornbrook Formation of Southern Oregon.
[Ward, Peter D., and Gerd EG Westermann. "First occurrence, systematics, and functional morphology of Nipponites (Cretaceous Lytoceratina) from the Americas." Journal of Paleontology (1977): 367-372.]
Image gallery
File:Nipponites mirabilis1.jpg, ''N. mirabilis''
File:Nipponites mirabilis & Ainoceras kamuy.jpg, ''N. mirabilis''
File:Nipponites mirabilis 2.jpg, ''N. mirabilis''
References
;Notes
;Bibliography
*
Ammonitida genera
Nostoceratidae
Cretaceous ammonites
Ammonites of Asia
Ammonites of Africa
Prehistoric animals of Madagascar
Turonian genus first appearances
Coniacian genus extinctions
Fossil taxa described in 1902
{{Ammonitida-stub