Geologically oldest oysters were epizoans on Early Triassic ammonoids
Furnish and Glenister (1970) described the Permian ammonoid
Cyclolobus from the Salt Range.
Through the climatic changes, conodont and ammonoid
faunae were initially able to recover very quickly during the Early Triassic as unusually short-lived species emerged.
Attachment of the body to the shell in ammonoids
. Abrupt diversification of species and genera occurred in the middle of the Artinskian (Bogoslovskaya 1986).
Analysis of heteromorph ammonoids
by differential geometry.
They evolved rapidly and, in some stratigraphic intervals, even somewhat more rapidly than Permian ammonoids
. Conodonts also exhibit a broader distribution than Permian ammonoids
because they are the only stratigraphically important Permian fossil group that is little affected by provincialism.
A contribution to the knowledge of Upper Devonian ammonoids
from the Holy Cross Mts.
Based on the scarce ammonoids
found in the middle part of the formation, Dubar and Mouterde (1957) and Suarez-Vega (1974) specify a late Kimmeridgian age (Eudoxus zone), and Ramirez del Pozo (1969) assigns an early Portlandian age to the upper part of the Lastres Fm.
The limestone contains bryozoans brachiopods bivalves gastropods ammonoids
trilobites crinoids and conodonts (Kummel and Teichert1970).
have an exceptionally good fossil record.
It was his work in the Canadian Arctic Islands, beginning in 1954, that laid the foundation for his subsequent brilliant career as a paleontologist and biostratigrapher specializing in the now-extinct class of coiled, marine molluscs known as ammonoids
Coprolites containing ammonoids
from the Devonian of New York.
The high diversity of one fossil group, the ammonoids
, has fueled efforts to understand the functional morphology of their phragmocones.
(3) Boyajian and Lutz (1992) documented patterns in hierarchical complexity at a smaller scale, within a substructure in the extinct ammonoids
secreted a coiled, chambered shell as they grew, and septa separating the chambers are visible externally in many fossil specimens as curvy lines or sutures [ILLUSTRATION FOR FIGURE 6 OMITTED].