Gabreyaspididae
| Gabreyaspididae Temporal range: Early Devonian
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| Reconstruction of Gabreyaspis | |
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| Family: | Gabreyaspididae
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Gabreyaspididae is a family of extinct amphiaspidid heterostracan agnathans whose fossils are restricted to Lower Devonian marine strata of Siberia near the Taimyr Peninsula.[1] In life, all amphiaspidids are thought to be benthic animals that lived most of their lives mostly buried in the sediment of a series of hypersaline lagoons. Amphiaspids are easily distinguished from other heterostracans in that all of the plates of the cephalothoracic armor are fused into a single, muff-like unit, so that the forebody of the living animal would have looked, in the case of gabreyaspidids, vaguely like a horseshoe crab with a pair of small, or degenerated eyes, with each flanked by a preorbital opening, and a simple, slit-like mouth positioned slightly ventrally.
Gabreyaspidids differ from the amphiaspidoid amphiaspids of Amphiaspididae primarily due to ornamentation unique to each family,[1] and differs from amphiaspidoid amphiaspids of Olbiaspididae in that gabreyaspidids' mouths are ventrally positioned, whereas the mouths of olbiaspidids are positioned anteriorly.
Taxonomy[edit]
Gabreyaspis[edit]
Gabreyaspis tarda is the type species of the family, and is known from several mostly complete cephalothoracic armors. It has a woodgrain-like ornamentation over its armor, with several tesserae-like units, especially around the head-region.
Prosarctaspis[edit]
Prosarctaspis taimyrica has a broad, flat, half-circle-shaped armor that looks vaguely like a horseshoe crab.
Pelaspis[edit]
Pelaspis teres differs from other gabreyaspidids in its unique ornamentation, the shape of its cephalothoracic armor, which is oval-circular, and suggestive of a pizza or a cookie, and its apparent lack of a dorsal spine.
Tareyaspis[edit]
Tareyaspis venusta is similar in size and dimensions to Pelaspis, but differs in ornamentation, and the shape of the posterior region of the cephalothoracic armor, which, in T. venusta, has a dorsal spine.
References[edit]
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