Machaeridia
 
   
                   
                                 
 
 

MACHAERIDIADescription from Adrain, 1992

General Description: Marine animals with a metamerically arranged, calcitic exoskeleton, composed of either two or four longitudinal series of posteriorly imbricated sclerites; individual sclerites composed of two distinct calcite layer; outer layer formed by lamellar deposition, bearing fine growth lines and coarser rugae developed parallel to growth lines; inner layer formed by terminal addition of calcite elements in series radiating outward from sclerite umbo; all sclerites with an inner groove running anteriorly from the umbo on the inner surface; muscle scar universally present on inner surface. Historically, Machaeridans have been regarded as echinoderms or possibly descendents of echinoderm ancestors.

Plumulites sp. – possibly P. trentonensis Withers – Description from Ruedemann, 1942

Description: Has kiteshaped plates that are short and broad. The apical part of the plate is not attenuated with proximal angles that are widely and almost equally truncated.

 

 
Plumulites sp., MCZ 145745   Plumulites sp., MCZ 145746   Plumulites sp., MCZ 145747
MCZ 145745: 9mm long
 
MCZ 145746: 7.5mm long
 
MCZ 145747: 9mm long
Plumulites, MCZ 145748  
MCZ 145748: 8mm long
       
 
 
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