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FOSSIL CARPOIDS FOR SALE
What Is A Carpoid?
Carpoids are enigmatic organisms. They are early echinoderms related to starfish and sea urchins. Unlike modern echinoderms, carpoids lack the five-fold radial symmetry and water vascular system. Carpoids were asymmetric or bilaterally symmetric. Like other echinoderms, they did possess skeletons of calcite plates. Depending on the species, they consisted of one or two ambulacra (filtering appendages), a theca (“head”) and a three section stele (“tail”). They are likely early ancestors of starfish and other echinoderms, but it is also possible that they are early ancestors of the Chordates: this is the phylum to which humans belong. This is a contentious theory based on the presence or absence of early gills in carpoids. Because these organisms are only known from fossils, gills are hard to identify accurately.
More Information: Academia.edu - Making sense of carpoids
What Did Carpoids Look Like?
Carpoids were unusual-looking organisms. The animal's vital organs were contained in a theca. Internal organs were surrounded by calcite plates. Depending on the species of carpoid, one or two ambulacrum extended from one end of the theca. These were appendages used to filter water for food. A mouth was located at the base of the ambulacrum if there was just one, or between them if there were two. From the other end of the theca, the three section stele (“tail”) extended. This was used either for locomotion or to hold the organism in place if sessile (fixed in one location). Carpoids likely grew up to about 4 inches (10cm).
When Did Carpoids Live?
Carpoids first evolved during the Middle Cambrian period and disappeared from the fossil record in the Early Devonian.
Carpoids In The Fossil Record
Complete carpoids are fairly uncommon fossils, though the individual calcite plates are frequently found. Some notable carpoid fossil localities include the Wheeler Shale in Utah for Middle Cambrian carpoids, the Ordovician formations in Southern Morocco, the Ordovician formations in Ontario, and the Early Devonian Hunsrück Slate in Germany.