| Powered by phpBay Pro |
Crinoid Fossils in Utah Mountains? Please help!?
One common fossil in the Wasatch Mountains, which you saw in the section introduction, is of an organism called crinoids, shown in the image below on the left. Crinoids lived in ancient shallow seas. When they died, their bodies fell down to the bottom of the seafloor and became preserved as fossils in the layers of mud and other sediments. Over time, those mud and sediment layers hardened into solid rock while the fossils remained intact.
Now, millions of years later, hikers in these high Utah mountains can find evidence of sea animals that lived there at one time. The crinoid fossils are found in many of the rocks that make up the mountains—evidence of what ancient environmental conditions were like. How do you think they got from the ocean floor to the mountains?
I have no idea how they got there. I tried researching and found nothing. I'd really appreciate the help. Thanks!
Crinoid Morphology
http://en.wikipedia.org/wiki/Crinoid
Morphology
A typical crinoid fossil, showing (from bottom to top) the stem, calyx, and arms with cirri
Crinoids comprise three basic sections; the stem, the calyx, and the arms. The stem is composed of highly porous ossicles which are connected by ligamentary tissue. The calyx contains the crinoid's digestive and reproductive organs, and the mouth is located at the top of the dorsal cup, while the anus is located peripheral to it. The arms display pentamerism or pentaradial symmetry and comprise smaller ossicles than the stem and are equipped with cirri which facilitate feeding by moving the organic media down the arm and into the mouth.
The majority of living crinoids are free-swimming and have only a vestigial stalk. In those deep-sea species that still retain a stalk, it may reach up to 1 metre (3.3 ft) in length, although it is usually much smaller. The stalk grows out of the aboral surface, which forms the upper side of the animal in starfish and sea urchins, so that crinoids are effectively upside-down by comparison with most other echinoderms. The base of the stalk consists of a disc-like sucker, which, in some species, has root-like structures that further increase its grip on the underlying surface. The stalk is often lined by small cirri.[2]
Like other echinoderms, crinoids have pentaradial symmetry. The aboral surface of the body is studded with plates of calcium carbonate, forming an endoskeleton similar to that in starfish and sea urchins. These make the calyx somewhat cup-shaped, and there are few, if any, ossicles in the oral (upper) surface. The upper surface, or tegmen, is divided into five ambulacral areas, including a deep groove from which the tube feet project, and five interambulacral areas between them. The anus, unusually for echinoderms, is found on the same surface as the mouth, at the edge of the tegmen.[2]
The ambulacral grooves extend onto the arms, which thus have tube feet along their inner surfaces. Primitively, crinoids had only five arms, but in most living species these are divided into two, giving ten arms in total. In most living species, especially the free-swimming feather stars, the arms branch several times, producing anything up to two hundred branches in total. The arms are jointed, and lined by smaller feather-like appendages, or pinnules, which also include tube feet.[2]
Items Recently Purchased From This Site:
| Powered by phpBay Pro |
Leave a Reply
You must be logged in to post a comment.