''Exiteloceras'' is an
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) ...
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 ...
from the
Late 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 ...
.
''Exiteloceras'' was proposed by
Alpheus Hyatt
Alpheus Hyatt (April 5, 1838 – January 15, 1902) was an American zoologist and palaeontologist.
Biography
Alpheus Hyatt II was born in Washington, D.C. to Alpheus Hyatt and Harriet Randolph (King) Hyatt. He briefly attended the Maryla ...
in 1894 for heteromorph ammonites with shells that are loosely coiled in a plane, early whorls varying from straight limbs connected by semicircular elbows to elliptical or nearly circular loops, later whorls being elliptical to circular. The whorl section is ovate with the dorsum on the inside curve broader than the venter on the outside. The ribs may be straight or