Group of problematic fossils
The Melanosclerites are a group of problematic microfossils obtained by palynological processing.
Morphology.
The form-taxon contains a wide array of rod-like fossils, 100 μm to some mm long, that culminate in a broad bulbous 'head', often separated from the stalk by a constriction. The bulbous end may bear broad 'prongs', giving the appearance of the end of a human femur where the prongs are paired, although the prongs often occur in higher number – five, six, a dozen – with some resemblance to "Namacalathus".
Affinity.
The affinity of melanosclerites is uncertain; algal has been proposed, but hydrozoan (cnidarian) is preferred, though not conclusively established.
"Melanoscleritoites" Eisenack, 1963 is interpreted as a hydrozoan, with other taxa not attributable to that particular class, on the basis of a broad morphological similarity – though the distinguishing features are far from unequivocal, and the preservation of the material raises some taphonomic problems. The composition resembles that of chitinozoans, scolecodonts, graptolites, and fungi – though at least one species of extant cubomedusan hydroid does produce a similarity resilient "chitinous" 'wall'.
Occurrence.
They have been reported in shallow marine sandstones and limestones, as well as upper slope and open marine sediments, in strata from the Lower Cambrian to Upper Devonian.
Taxa include:
References.
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