Burlingiid trilobites from Norway, with a discussion of their affinities and relationships

Abstract

ABSTRACT. Four Middle and Upper Cambrian burlingiid trilobites from the Oslo Region, Norway, are described including Burlingia angusta sp. nov. from the Ptychagnostus punctuosus Zone and Schmalenseeia athrotryphe sp. nov. from the lower part of the Lejopyge laevigata Zone. New complete material previously attributed to Schmalenseeia jagoi Whittington is assigned to Burlingia. Cladistic analysis supports the genera Burlingia and Schmalenseeia as currently understood, including the placement of the controversial middle Middle Cambrian Schmalenseeia acutangula Westerga Êrd in Schmalenseeia, even though it lacks typical characters of the genus such as the median ridge on the preglabellar ®eld. The analysis also supports burlingiid monophyly, and suggests that Schmalenseeia was derived from a broadly Burlingia-like ancestor, with S. acutangula displaying how the transition may have occurred. The broader relationships of Burlingia remain obscure, although similarities between burlingiids and the arthropod Kleptothule from the Early Cambrian Sirius Passet fauna are discussed: these include overall form, lack of functional hinges in the thorax, and details of the cephalic region. It is unclear whether these similarities represent general progenetic features, are functional convergences or, less likely, represent a genuine relationship.

The Burlingiidae (Trilobita): revised generic composition, stratigraphy, and the first species from the early Middle Cambrian of West Gondwana

“…primitiva Zhao, Yuan & Ahlberg in Yuan et al, 2002;B. multisegmenta Zhao, Yuan & Ahlberg in Yuan et al, 2002;and B. balangensis Yuan & Esteve, 2015; all four from the Kaili Formation of southeastern Guizhou); and Baltica (B. laevis Westergård, 1936, from the Acadoparadoxides pinus Zone of Ö land, Sweden; B. jagoi (Whittington, 1994) from the Oslo region of Norway and Scania, Sweden; and B. angusta Ebbestad & Budd, 2003, from the Oslo region of Norway). Burlingia laevis has been synonymized with Burlingia hectori by Whittington (1994), but this assumption is challenged herein (see remarks below).…”

“…Three species existed in Baltica: S. amphionura Moberg, 1903 (Fig. 1A, B); S. acutangula Westergård, 1948 (revised below); and S. athrothryphe Ebbestad & Budd, 2003, from the Oslo region, Norway. S. amphionura has not only been found in the Swedish regions of Ö land, Scania, Jämtland and Gotland (see Ahlberg 1989), but has also been reported from England (Taylor & Rushton 1972;Rushton 1978), the Indian Himalayas (Jell & Hughes 1997) and Siberia (Chernysheva 1960).…”

Exotic trilobites from the uppermost Cambrian Series 3 and lower Furongian of Sweden

“…Among the taxa examined, those characteristic of East Gondwana include representatives of Maladioidella, Protemnites, Westergaardella and Ptychoparia. Species with such affinities that also occur in Scandinavia in the studied interval include Palaeadotes dissidens Öpik, 1967, Paradamesella eremita (Westergård, 1947, Schmalenseeia amphionura Moberg, 1903, Proceratopyge similis Westergård, 1947, P. nathorsti Westergård, 1922and P. tullbergi Westergård, 1922(Westergård 1922, 1947bWhittington 1994;Zhang 1996;Ebbestad and Budd 2003;Text-fig. 3 fig.…”

“…Apart from Baltica, burlingiids of the genus Schmalenseeia Moberg, 1903 occur in Siberia, Avalonia, and Gondwana (Australia, China and the Himalayas) (Text- fig. 8; see also Whittington 1994;Ebbestad and Budd 2003).…”

“…Phase 1 is recorded in the uppermost Cambrian Series 3 and coincided with the appearance of the agnostoiddominated fauna of the Agnostus pisiformis Zone, separating the agnostoid-paradoxidid-solenopleuridconocoryphid assemblages of the Scandinavian Middle Cambrian and the olenid assemblages of the Furongian. The exotic trilobites in this phase include: the damesellids Paradamesella eremita (Westergård, 1947) and Palaeadotes dissidens Öpik, 1967Öpik, (Zhang 1996; the burlingiid Schmalenseeia amphionura Moberg, 1903(Ahlberg 1989Whittington 1994;Ebbestad and Budd 2003); the ceratopygids Proceratopyge similis Westergård, 1947 and Proceratopyge nathorsti Westergård, 1922(Westergård 1922, 1947b; the aphelaspidids Aphelaspis sp. A and Aphelaspis sp.…”