Brancoceratidae
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Brancoceratidae is a family of acanthoceratoid
ammonites 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 cuttl ...
from the middle of the
Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, recognized by their commonly evolute shells with round, oval, or quadrate whorls, strong ribs, usual ventral keels, and at least, umblical tubercles. The family is thought to be derived from the
Desmoceratidae Desmoceratidae is a family belonging to the ammonite superfamily Desmoceratoidea. with and (1996), ''Mollusca 4 Revised , Cretaceous Ammonoidea'', vol. 4, in ''Treatise on Invertebrate Paleontology'', Part L (Roger L. Kaesler et el. eds.), ...
(Desmoceratoidea), perhaps from '' Silesitoides'' or some allied genus.


Subfamilies

The Brancoceratidae are divided into three subfamilies, described as follows. Brancoceratinae Spath, 1933: Generally small, evolute with round, oval, square or rectangular whorl sections. The venter may be sharp on the inner whorls, a feature which disappears on the later. Ribs are strong and rounded, and commonly cross over the venter. Sutures are simple, pseudoceratitc in some. The subfamily lived from during the Albian. Mojsisovicziinae Hatt, 1903: derived from the Broncoceratinae, beginning with '' Mojsisoviczia'', in which the keel has become a stable character, in some appearing only early, in others appearing only late. There are two main stocks, one of high-whorled compressed forms which left no descendants, the other, more evolute with round or square whorl sections, which gave rise to the Mortoniceratinae. Both stocks have their origin in ''Mojsisociczia''. Mojsisovicziinae genera lived from the Middle to Late Albian. Mortoniceratinae Spath, 1925: Moderately involute to very evolute brancoceratids with more or less rounded, square, or compressed whorls; low or high keels and ribs that branch, at last on the early whorls but may be single on the body chamber or even earlier. Ribs are low and round, or flat, to high and round, but never high and sharp. Tubercles, typically present, may number as many as five per rib. The suture is generally with squarish, symmetrical, deeply and sharply indented saddles. Mortoniceratinae genera are the youngest in age living from the late Middle Albian to the Early Cenomanian in the Late Cretaceous.


References

* *Ryszard Marcinowski and Jost Wiedmann.The Albian Ammonites of Poland. Palaeontologia Polonica no. 50, 1990 Ammonitida families Acanthoceratoidea Albian first appearances Cenomanian extinctions {{Ammonitina-stub