Fossil eggs
of probable piscine origin preserved on Pennsylvanian Sphenopteridium
foliage from the Kinney Quarry, central New Mexico
Sergius
H. Mamay, Journal of Vertebrate Paleontology, 1994, 14(3):320-326
The Upper Pennsylvanian sedimentary rocks exposed in the Kinney Brick Company quarry, central New Mexico, contain a diverse megaflora with abundant foliage of the pteridosperm Sphenopteridium manzanitanum. A few of the frond fragments carry many small (to 2.0 mm in diameter), compressed spherical bodies, which occur as linear or random groups on both foliar rachises and laminae; also present are two compact, isolated aggregates not attached to any organic substrate. The individual bodies are delimited by a thin, amorphous wall that evidently was membranous, flexible, and adhesive, forming flattened areas of mutual contact. These bodies are interpreted as animal eggs. Their association with spirorbid worm tubes and other evidence indicates that the eggs were deposited under water, on floating or suspended vegetation or in compact, unattached masses. Neither terrestrial nor aquatic invertebrates yield satisfactory clues as to the egg source. However, the aquatic or semiaquatic vertebrates (fishes and amphibians) are both feasible candidates, with the preponderance of evidence of comparative egg morphology and ovipositing strategies weighing in favor of a probably chondrostean origin for the Kinney eggs. They represent the oldest known vertebrate egg masses.