Agnostus

Cambrian-Ordovician

A tiny trilobite, usually less than 5 mm in length, with an unusual head and tail and only two thoracic segments. The species had no eyes or facial suture. Rare occurrences of this animal with preserved soft parts suggest that it was an active swimmer, which usually adopted a partly enrolled shape (see Fig. 8.4). It likely fed on material suspended above very soft sea floors and was typical of deep water assemblages.

Trinucleus

Ordovician

A blind trilobite with a wide fringe developed around the front of the cephalon; this likely had a sensory function. Genal spines extended from the fringe towards the rear of the animal. The glabella was inflated, suggesting that the stomach below would also have been large. In addition, the thorax would have been well above the sea bed in life. These two adaptations suggest that the species was a filter feeder, suspending sediment in water below the body and then eating a mixture of mud and food, which was processed in the large stomach. The thorax is relatively small, with six segments, and the pygidium is also small. Specimens tend to be small, 2-4 cm in length.

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  • J
    What did agnostus eat?
    8 years ago

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