Phylum Echinodermata
 
 
               
                           
                           
 

   

 

The echinoderm fauna of the Upper Trenton Group is best developed in the crinoid beds in the Spillway Member of the Rust Formation at Walcott-Rust Quarry where the fauna includes 11 described species of crinoids, one paracrinoid, one rhombiferan, two “carpoids”, two asteroids, one ophiuroid, and one edrioasteroid. The specimens from the Museum of Comparative Zoology that are illustrated here were collected by Charles Doolittle Walcott and William P. Rust in the late 1800s and Thomas E. Whiteley in the 1990s. Some of the echinoderms are also rare to common in similar facies from the Upper Trenton at other localities in the West Canada Creek area. The echinoderm fauna consists of four basic assemblages. The disparid crinoids Cincinnaticrinus varibrachialus and Ectenocrinus simplex dominate the most common one. In addition, largely monospecific associations of the disparid crinoid Iocrinus trentonensis , the camerate crinoid Rhaphanocrinus subnodosus , and the rhombiferan Cheirocystis anatiformis are known. Small numbers of other echinoderm taxa can be found in any of the main assemblages. Diversified trilobites, brachiopods, and bryozoans also occur with the echinoderms.

Preservation of many of the Walcott-Rust Quarry echinoderms is excellent and encourages the reconstruction of paleobiology. Food grooves and covering plates are available for all of the common crinoids and the rhombiferan and these reflect the nature of their tubefeet and the size ranges of the food particles eaten by these suspension-feeding animals. The few complete specimens show the nature of attachment devices and substrates and provide insights about the levels occupied by some of the crinoids and the rhombiferan. The “carpoids”, starfish, and, the edrioasteroid were restricted to the seafloor. The inferences about living habits are discussed for each species subsequently.

 

   
 
 
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© 2004 President and Fellows of Harvard College
Specimen of Atelocystites cf. A. huxleyi, MCZ 128266 Specimen of Edrioaster? sp., MCZ 125601 Specimens of Cheirocystis anatiformis, MCZ 145751 and MCZ 145752 Specimen of Rhaphanocrinus subnodosus, MCZ 113448 Specimens of Macroporaster matutinus, MCZ 108055, MCZ 146701, and MCZ 146702