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However, land snails and their relatives were rare before the Cretaceous period. [39] In Mesozoic rocks, gastropods become more common in the fossil record, with well-preserved shells. Fossils are found in ancient beds from both freshwater and marine environments.
Ammonoids are excellent index fossils, and they have been frequently used to link rock layers in which a particular species or genus is found to specific geologic time periods. Their fossil shells usually take the form of planispirals , although some helically spiraled and nonspiraled forms (known as heteromorphs ) have been found, primarily ...
Fossils of many types of water-dwelling animals from the Devonian period are found in deposits in the U.S. state of Michigan. Among the more commonly occurring specimens are bryozoans, corals, crinoids, and brachiopods. Also found, but not so commonly, are armored fish called placoderms, snails, sharks, stromatolites, trilobites and blastoids.
This list of marine gastropod genera in the fossil record is an attempt to list all the genera of sea snails or marine gastropod mollusks which have been found in the fossil record. Nearly all of these are genera of shelled forms, since it is relatively rare for gastropods without a shell ( sea slugs ) to leave any recognizable traces.
†Nerinea is an extinct genus of fossil sea snails, marine gastropod molluscs in the clade Heterobranchia. ... Fossils are known from various localities of Europe ...
Fossils discovered in southern China of a curious little marine creature that lived during the Cambrian Period about 514 million years ago - essentially a spiny slug - are now providing some ...
This genus is known in the fossil records from the Cretaceous to the Quaternary (age range: from 125.45 to 0.0 million years ago). Fossils of species within this genus have been found all over the world. There are about 25 known extinct species. [4] Murex altispira Fossil shell of Murex spinicosta from Pliocene of Italy
Abatocrinus † Abatocrinus grandis † Acanthocrania † Acantholaminatus † Acantholaminatus multistylus † Acantholaminatus typicus † Acodus † Actinoceras † Actinoceras capitolinum † Actinoceras cuvieri † Actinoceras tenuifilum † Actinocrinites † Adinocrinus † Agaricocrinus Fossilized calyx of the Carboniferous crinoid ("sea lily") Agaricocrinus americanus, or the mushroom ...