Persistent Form

Persistent Form

 

an organism that has maintained a constant external appearance in the course of evolution, passing from one epoch to another without substantial changes. Persistent forms are often called living fossils, or phylogenetic relicts. Examples include a brachiopod of the genus Lingula and king crabs of the genus Limulus, both of which have existed for about 400 million years; a marine mollusk of the genus Neopilina, which has existed for 350 million years; and a lungfish of the genus Latimeria, which has existed for about 250 million years. The occurrence of persistent forms is always due to the stability of the principal features of the organisms’ environment. A closely related term is “bradytelic forms” (seeBRADYTELY).

References in periodicals archive ?
In the past researchers have found dying organisms near the surface and remnants of DNA but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said.
In the past, researchers have found dying organisms near the surface and remnants of DNA, but this is really the first time that anyone has been able to identify a persistent form of life living in the soil of the Atacama Desert," Schulze-Makuch said.
Although records indicate that only one white woman was in the camp in question, compared to 165 black women, the specter of the rape of white women was enough to end the state's most persistent form of punishment.
Rodney Brown drilled toward the top corner, forcing a brilliant save from Andy Coleman and James McGonigle was in persistent form.
Of the many ways the Chinese have honored the dead through the centuries, says Davis, muzhiming, entombed epitaph inscriptions, have proved to be the most versatile, widespread, and persistent form employed in medieval elite burials and those of later eras as well.
7,8 Vaginal discharge, especially persistent form, is very rare; therefore it is generally neglected in these cases.
About 1 percent have a severe, persistent form known as hyperemesis gravidarum, which can lead to malnutrition.
Canadian, and Mexican highways are a persistent form of hidden protectionism.
Hanne, who's now wheelchair bound thanks to an assassin's bullet in her spine, is on sparklingly grumpy but persistent form.
A MORE persistent form of a deadly superbug has been discovered in hospitals in South Wales.
A MORE persistent form of a potentially deadly superbug has been discovered in half of Wales' hospitals.

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