Infaunal moulting in trilobites and escalatory responses against predation.

RUSTAN, J.J.; BALSEIRO, D; WAISFELD, B.G.; FOGLIA, R.D.; VACCARI, N.E.,

GEOLOGY

GEOLOGICAL SOC AMER, INC

Lugar: Boulder; Año: 2011 vol. 39 p. 495 - 498

0091-7613

The outstanding fossil record of trilobites contrasts with our limited knowledge of their life styles and strategies. Aspects such as infaunalism and behavioral defensive skills in this group have yet to be demonstrated conclusively. New insights are here reported based on a striking sclerite configuration exhibited by three phacopid trilobite species, which are part of a Late Silurian-Early Devonian Paciphacops (Paciphacops) Maksimova, 1972, lineage. An unusual moult pattern provides a compelling evidence of infaunal behavior which accounts for a hiding, anti-predatory adaptation. In addition, strengthening of the exoskeleton and acquisition of spines, indicate an evolutionary trend toward morphological defensive strategies. Both, trends in active and passive traits, are considered escalatory in nature, thus providing unequivocal support for understanding the ecological role of trilobites as a main prey-group in the context of the global diversification of predators recorded during mid Paleozoic times.