ammonoid

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ammonoid

(ăm′ə-noid′)
n.
An extinct cephalopod mollusk of the subclass Ammonoidea of the Devonian to Cretaceous Periods, having a straight or coiled chambered shell characterized by more or less intricate suture patterns where the septa between individual chambers join the outer shell wall.
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References in periodicals archive ?
3) Ammonoids evolved to have more complex suture patterns--and, thus, stronger shells--through time.
Tim retired in 1995, but not before completing a monumental work, Canadian Triassic Ammonoid Faunas (Tozer, 1994), at 663 pages with 148 plates the largest paleonto-logical treatise ever published by the GSC.
Septal complexity in ammonoid cephalopods increased mechanical risk and limited depth.
The mean complexity of a substructure increased in ammonoids over the first part of their history, but declined after that.
Ammonoids are generally rare and sparsely distributed throughout the Lower Cretaceous succession of the Maestrat Basin.
One of the underlying goals of the present study was to give undergraduate students hands-on experimental involvement by having them compare their research and findings with the important earlier work on the coiling of ammonoids presented by David Raup (1967) in The Journal of Paleontology.
Occurrence of ammonoids in the Jurassic deposits represents a conventional tool for bio(chrono)stratigraph ical dating and allows excellent basis for correlation with other areas.
Among the ammonoids, the ceratites replaced the goniatites, the tetracoralaria gave way to the exacoralaria that currently continue to form the coral reefs, and other groups like trilobites and fusulines disappeared forever.