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Sand dollars diverged from the other irregular echinoids, namely the cassiduloids, during the early Jurassic, [5] with the first true sand dollar genus, Togocyamus, arising during the Paleocene. Soon after Togocyamus, more modern-looking groups emerged during the Eocene. [1] Sand dollars are small in size, averaging from 80 to 100 mm (3 to 4 ...
Clypeasteridae is a family of sea urchins in the order Clypeasteroida.This family was first scientifically described in 1835 by the Swiss-American biologist Louis Agassiz.. The clypeasteridae also known as the sand dollar, are round and semi-flat organisms with spines lining the underside of the body and elongated genital papillae aiding its survival and reproduction.
Rotulidae is a family of small sand dollars native to the Atlantic coast of Africa, with 3 genera, with Rotula and Heliophora being extant, the other, Rotuloidea, being extinct since the Pliocene, but all three being found in the fossil record along the Atlantic African coast since the Miocene.
The tests (shells) of these sand dollars are round, flat and disc-like, typically measuring 3 inches (7.6 cm) in diameter. The growth rate for this animal is between 3.5 to 6 mm/yr in the latter 5 years of their lifespan, and the lifespan is typically around 8 years. [2]
Heliophora orbicularis, also known as the West African Sand Dollar, is a small sand dollar in to the family Rotulidae, and the only species in the genus Heliophora. It, and other members of Rotulidae have been found in West African marine strata from the Late Miocene onward.
A quarterly literary magazine, The Threepenny Review publishes nonfiction essays, memoirs and reviews, fiction stories and poetry in print. Depending on the type of piece, you can expect between ...
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Clypeaster australasiae, the Australasian sand dollar, is a species of sea urchins of the family Clypeasteridae. Their armour is covered with spines. Their armour is covered with spines. Clypeaster australasiae was first scientifically described in 1851 by Gray.