Clonograptus

Clonograptus

▪ graptolite genus
      genus of graptolites (extinct, small floating colonial animals related to the primitive chordates), characterized by a frondlike form. Groups of these animals were connected by stalklike structures to a central region. Various forms or species of Clonograptus are important guide, or index, fossils for the correlation of Ordovician rocks (505 to 438 million years ago).

* * *


Universalium. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Clonograptus — Graptolites, like this Amplexograptus from the Ordovician near Caney Springs, Tennessee are good zone fossils. A zone fossil must have a short time span but a common animal of the time. Graptolites became extinct at the end of the Devonian.… …   Wikipedia

  • TRÉMADOC — Premier étage du «Silurien» gallois nommé par A. Sedgwick en 1846, le Trémadoc (ou Trémadocien) correspond aux couches de passage entre le Cambrien et l’Ordovicien, auquel il appartient. Dans l’est de l’Amérique du Nord, il prolonge le Cambrien… …   Encyclopédie Universelle

  • ТРЕМАДОКСКИЙ ЯРУС — [по пос. Тремадок в Уэльсе], Sedgwick, 1852, н. ярус ордовикской системы Северо Европ. палеозоогеографической пров. Подразделяется на 2 подъяруса: для нижнего характерно наличие диктионемовых сланцев с Dictyonema flabelliforme Еiсhw.,… …   Геологическая энциклопедия

  • graptolite — graptolitic /grap teuh lit ik/, adj. /grap teuh luyt /, n. any colonial animal of the extinct class Graptolithina, most common in the Ordovician and Silurian Periods, thought to be related to the pterobranchs. [1830 40; < Gk graptó(s) painted,… …   Universalium

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”