Infaunal molting in Trilobita and escalatory responses against predation

Recognising moulting behaviour in trilobites by examining morphology, development and preservation: Comment on Błażejowski et al. 2015

“…Paciphacops is thought to utilise infaunal moulting (following burrowing for protection from predators), which occurs through an anterior gape suture created by ventral disarticulation of the cephalon and thorax, causing the cephalon to hinge dorsally at an angle of nearly 90° (Ref. , Fig. ; our Fig.…”

“…Paciphacops is thought to utilise infaunal moulting (following burrowing for protection from predators), which occurs through an anterior gape suture created by ventral disarticulation of the cephalon and thorax, causing the cephalon to hinge dorsally at an angle of nearly 90˚(Ref. [17] Other phacopid trilobite specimens also show possible infaunal moulting with their cephala angled at more than 90f rom the sediment [18]. However, the specimen of T. chopini (Ref.…”

“…2-6), and therefore a more convincing moult-carcass assemblage would have the carcass preserved entirely in front of the moult on a [9]. D: In comparison to C, the positioning of the labelled 'carcass' and 'moult' suggested for a true moult-carcass assemblage [17]. E: One of several Trimerocephalus 'queues' of overlapping trilobite carcasses from the Holy Cross Mountains, adapted from Plate 2, Fig.…”

“…Scale bar 2 cm, as given in Błażejowski et al . D: In comparison to C, the positioning of the labelled ‘carcass’ and ‘moult’ suggested for a true moult‐carcass assemblage . E: One of several Trimerocephalus ‘queues’ of overlapping trilobite carcasses from the Holy Cross Mountains, adapted from Plate 2, Fig.…”

The oldest record of predation on echinoids: evidence from the Middle Jurassic of Poland

“…() suggested that predation might be a driving force in the evolution of crinoid clades, whereas Vermeij (), like many other authors, suggested that the infaunalization of echinoids and other groups (Rustán et al . ) was a response to predation pressure. Huntley & Kowalewski () hypothesized that predation might have had an effect on the diversity of organisms with respect to various clades, including echinoids.…”