ammonoid


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Related to ammonoid: ammonite, Ammonoidea
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  • noun

Synonyms for ammonoid

one of the coiled chambered fossil shells of extinct mollusks

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London, December 22 ( ANI ): Marine animal groups like ammonoids and conodonts already peaked three or four million years earlier, namely still during the Ear-ly Triassic, researchers say.
However, due to a small sample size, poor or even erroneous stratigraphic control, as well as inadequate identification of the previous collections, the previous studies failed to establish well-defined levels of ammonoid genera or assemblages.
Tithonian ammonoid biostratigraphy in eastern Himalayan Tibet // Geobios-Lyon.
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.
2) One of the chambers of the ammonoid was used as a living space and the rest were used to regulate buoyancy, just like in a submarine.
1) Ammonoids have an exceptionally good fossil record.
3) Ammonoids evolved to have more complex suture patterns--and, thus, stronger shells--through time.
4) Ammonoids were devastated by the largest extinction in Earth's history, at the end of the Permian Period, as well as Late Cretaceous mass extinction.
Ammonoid shell streamlining was studied by Kummel and Lloyd (1955) using a circulating water channel and plaster models of ammonoid shells.
During the Devonian Period, the ammonoid cephalopods radiated and diversified and they survived repeated episodes of mass extinction followed by rapid diversification.
Further, only the best illustrations were used for calculating ammonoid dimensions (Raup, 1967).
The underlying goal of this project was to teach students about ammonoid coiling strategies by having them measure ammonoid cross-sectional geometry and calculate the variety of coiling approaches, W and D.
Students were required to take all the following measurements for each appropriate ammonoid in their assigned floor space (a, c, d, e; Figure 2) and calculate W and D.
After characterizing the range of variation in spiral form for these ammonoids, the data set was analyzed with respect to four criteria: (1) shell strength, (2) shell streamlining and hydrodynamic performance, (3) carbonate efficiency, and (4) ammonoid stability.
Four hundred ammonoid cross sections were measured and plotted in this study.