|Sent on:||Thursday, June 13, 2013 2:51 PM|
The impressions are made from your molds of authentic tracks? That's very cool, Glen!
"Living Fossil" is an informal term that can have a couple different meanings. Often it is used broadly to refer to any species or group that appears to have changed little from its fossil ancestors, which would include dozens of organisms, including forms like the horseshoe crab, whose modern form is a lot like ancient species, including some over 400 million years old. Other examples would include various groups of fish (like sharks and gars), some lizards that are very similar to Mesozoic forms, etc.
The term "living fossil" can also be used in a more narrow sense to refer to a species or group thought to have been extinct for millions of years, but which turns up alive today, such as the Coelacanth or Ginkgo. However, there is also a specific term for these cases: "Lazarus taxa", referring to Lazarus in the Bible, who Jesus reportedly raised from the dead.
Speaking of fossils... I want to let the group know that at the next meeting of the North Coast Fossil Club this Saturday morning at 10:00 a.m. at the Brooklyn Branch of Cuy. Pub Library on Ridge Rd, the speaker will be paleontologist Hans Thewissen, arguably the world's leading authority on fossil whales. He has personally found and described a number of intermediate forms that have greatly expanded our knowledge of whale evolution (and which give creationists fits). The meeting is open to the public, and I'd like to invite everyone to join us. Hans has spoken to our fossil club several times before, and is always very interesting.
For more info see the club web site at http://ncfclub.org/
Also on the web site is a link to more photos on the dinosaur trackways I've been working on at Brunswick Lake (behind the Giant Eagle on 303). It's a long walkway with several types of dinosaur tracks impressed in concrete. They proceed from from the oldest to youngest, so as you travel up the path, you are essentially walking through time. I recently finished sealing the tracks, and they are ready for public viewing (except for a sign, which we hope to install soon). Among the trails is a series of elongate, metatarsal dinosaur tracks of the kind once mistaken for "human" tracks in Texas (when their digits are subdued by mud collapse or infilling, which is the case with the second track in the series).
Also included in the walkway are impressions of various ammonites, which are prehistoric squid-like creatures with coiled shells. Ammonites went extinct with most dinosaurs, but a close relative (the Chambered Nautilus) is still alive today, and can be considered a "living fossil." I said "most dinosaurs" because according to most paleontologists today, birds are not only the descendents of dinosaurs, but are themselves dinosaurs (a group of feathered theropods). To help illustrate this, the last "dinosaur" trail in the Brunswick walkway is of a Moa (giant flightless bird) from New Zealand, which was apparently hunted to extinction only several hundred years ago. We're hoping to have a ribbon cutting ceremony for July 4th (if we can get the sign done by then), but your all invited to stop by the trackway at any time. Thanks!
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