(LINKS TO PAST FOSSIL FRIDAYS)
Community
College (LRCCD)
Geology & Earth Science Instructor: Arthur
Reed, P.G.
Happy Fossil Friday!
Friday June 25, 2021
Tardigrades
Fossils
from Cambrian, tough enough to survive as a species to the end of Earth?!
Tardigrades,
are known colloquially as water bears or moss piglets. Fossils of nearly identical creatures have
been found from the Cambrian period over 500 million years ago, when the first
complex animals were evolving. And, ever since they were discovered in 1773 by
German pastor Johann August Ephraim Goeze it has been clear they are
special.
These particular fossils (≈1.5 mm) show us the very patchy fossil record of tardis
must be due to them not fossilize easily.
The
earliest known true members of the group are from Cretaceous (145 to
66 million years ago) amber found in North America, but are essentially modern
forms, and therefore likely have a significantly earlier origin, as they
diverged from their closest relatives in the Cambrian over 500 million
years ago.
The above fossils were embedded in limestones, and
thus could eventually be recovered by etching them out of the rock in which
they were found using weak acids, as the fossils (replaced now by fluoritic
apatite) do not dissolve.
The
biggest adults may reach a body length of 1.5 mm, the smallest below
0.1 mm. Newly hatched tardigrades may be smaller than 0.05 mm.
Tardigrades
have survived all five mass extinctions, laboratory
temperatures from near absolute zero to 150°C, and atmospheric vacuum and cosmic radiation on the
outside of a spaceship. This fits into
the hypothesis some scientists hold that life may have traveled on debris
between our planets in the past.
Adapted from:
University of Manchester, UK