The trilobiteProtostygina and the composition of the Styginidae, with two new genera

Holloway, David J.

doi:10.1007/bf02988377

Cited by 15 publications

(12 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, as pointed out by Whittington (1999) and Schraut and Feist (2004), the scutelluids differ from the styginids in having a different pattern of glabellar impressions, articulating half-rings with terrace ridges, hinges on the adaxial pleurae, and 7 paired pleural ribs besides a single, often bifurcated, median one in the pygidium, all features displayed by Paralejurus. In addition, the first Paralejurus do not appear prior to the Devonian, and are thus much later than typical "flat" scutelluids which are known since the Early Ordovician (Whittington 1997(Whittington , 2000Holloway 2007). The extended pygidium in scutelluids has unique morphological characteristics (e.g.…”

Section: Systematic Position Of Paralejurusmentioning

confidence: 94%

See 1 more Smart Citation

Coaptative devices, enrollment, and life habits in Paralejurus, a particular case in scutelluid trilobites

Feist

Lerosey‐Aubril

Johnson³

2010

Palaeobio Palaeoenv

View full text Add to dashboard Cite

The first completely enrolled adult scutelluids assigned to the Paralejurus brongniarti group (Pragian) and to Paralejurus rehamnanus (Emsian) from southern Morocco are described. The Pragian taxon exhibits volvation in the sphaeroidal mode and a simple morphological configuration of the external thoracic pleurae with edge to edge fit between each other and against both the posterior edge of the genae and the anterior edge of the pygidium, respectively. Evolutionary trends towards perfect tightness of enrollment and the avoidance of lateral shearing are obvious in later Moroccan Paralejurus such as P. rehamnanus and allies from the Lower/Middle Devonian transition. In these forms, coaptative devices, such as submarginal grooves on the posterior edges of the genae and external thoracic pleurae, ventral fulcral processes and sockets, as well as bulging of the anterolateral pygidial doublures and corresponding depressions in genal doublures, were developed. The possible role of terrace ridges to assist in coaptation and/or to obtain hermetic closure of articulation gaps during volvation is discussed. Morphological and behavioural traits point to a semi-endobenthic lifestyle of Paralejurus with enrollment being an exceptional defence strategy against predatory attack. These traits that differentiate Paralejurus from all other scutelluid taxa are regarded as ecological rather than phylogenetical in origin. Consequently, the assignment of Paralejurus to the subfamily "Paralejurinae" within the Scutelluidae is favoured.

show abstract

Section: Systematic Position Of Paralejurusmentioning

confidence: 94%

“…Taking into account proper evolutionary trends that characterise the Paralejurus group, we consider them to constitute a subfamily "Paralejurinae" assigned to the Scutelluidae (sensu Richter 1955, 1956;Holloway 2007) rather than to the Styginidae.…”

Section: Systematic Position Of Paralejurusmentioning

confidence: 99%

Coaptative devices, enrollment, and life habits in Paralejurus, a particular case in scutelluid trilobites

Feist

Lerosey‐Aubril

Johnson³

2010

Palaeobio Palaeoenv

View full text Add to dashboard Cite

show abstract

“…If the styginid-scutelluid group originated independently from illaenids and panderiids (Whittington 1997a), smooth pleurae also developed independently, by parallel evolution. As mentioned above, the earliest members of this clade have the pleural furrows present, at least in young growth stages (Whittington 1950(Whittington , 1963Holloway 2007).…”

Section: Svobodapeltis and The Earliest Illaenoidsmentioning

confidence: 98%

“…-Pleural furrows: Holloway (2007) noted that thoracic pleural furrows are present in the styginids Perischoclonus Raymond, 1925(see Whittington 1963 and Bronteopsis Salter, 1866(see Ingham & Tripp 1991, but these genera are exceptions in comparison with others referred to the Illaenoidea. Unlike the majority of illaenoids, the pleural furrows are clearly developed in all thoracic segments of a holaspid specimen of Svobodapeltis (Fig.…”

Section: Genus Svobodapeltis šNajdr 1957mentioning

confidence: 99%