Macropyge (Promacropyge) scandinavica new species; the first macropyginid trilobite recorded from the Furongian of Baltica

Abstract

Macropyge (Promacropyge) scandinavica new species is described from the Furongian Peltura minor Zone on northwestern Mount Kinnekulle, southcentral Sweden. It represents the first macropyginid trilobite recorded in Baltica. M. (P.) scandinavica closely resembles other species of the same subgenus from southeast China, suggesting a correlation between the Scandinavian P. minor Zone and the Lotagnostus americanus-Hedinaspis regalis Zone of China. The specimens are preserved in two limestone lithologies, interpreted as representing alternating normal and storm deposits, supporting the idea of an intrabasinal paleohigh in Västergötland, southcentral Sweden.

Intraspecific variation and taphonomic alteration in the Cambrian (Furongian) agnostoid Lotagnostus americanus: new information from China

“…Ludvigsen & Westrop's (1989 synonymy was followed by Peng & Babcock (2005), who synonymized additional species based on morphologic variation observed in Lotagnostus material described from other regions. The synonymy of Peng & Babcock (2005) has been widely adopted (Terfelt & Ahlgren 2007;Terfelt et al 2008;Lazarenko et al 2008aLazarenko et al , b, 2011Rushton 2009;Ahlberg & Terfelt 2012). Rushton (2009, p. 276) added one more species, Lotagnostus sanduensis Lu & Chien (in Lu & Qian 1983), to the synonymy of L. americanus.…”

“…This view contrasts with evidence published by many specialists, who have long noted that many agnostoids have similar morphologies and similar ranges of morphology in collections made from widely separated areas of the world (e.g. Daily & Jago 1975;Rushton 1978;Ergaliev 1980Ergaliev , 1983Lu & Lin 1980Robison 1982Robison , 1984Robison , 1994Shergold et al 1990;Peng 1992;Pratt 1992;Shergold & Laurie 1997;Peng & Robison 2000;Ahlberg 2003;Choi et al 2004;Peng et al 2004Peng et al , 2009Peng et al , 2012cPeng & Babcock 2005;Babcock et al 2007;Jago & Cooper 2007;Lazarenko et al 2008aLazarenko et al , b, 2011Terfelt & Ahlberg 2010;Terfelt et al 2011;Ahlberg & Terfelt 2012). Evidence of species that were broadly distributed in open-shelf lithofacies accords well with the interpretation that many agnostoids, at least in their juvenile stages, were nektic or pelagic.…”

“…In their view, the first recorded appearance of L. americanus in Sweden "may not accurately record an origination" because it appears immediately above a "faunal discontinuity . This argument was based on information carried forward from older literature (e.g., Ahlberg 2003, Terfelt et al 2011. However, based on a review of all known occurrences of Lotagnostus in Västergötland and Skåne, Sweden, the lowest observed occurrence of L. americanus in Sweden is near the base of the Ctenopyge tumida polymerid zone (Babcock et al 2012).…”

A potential GSSP for the base of the uppermost Cambrian stage, coinciding with the first appearance of Lotagnostus americanus at Wa'ergang, Hunan, China

“…They include the widely distributed agnostoid Neoagnostus bilobus, and the polymerids Skljarella hunanensis and Macropyge (Promacropyge) ciliensis. S. hunanensis and M. (P.) ciliensis are so far recognised only from NW Hunan, but similar species, some of which may be synonymous, are known from other localities in China (Guihzou, Xinjiang and Zhejiang), Kazakhstan, Siberia, Tasmania and Sweden (Yin & Lee 1978;Zhang 1981;Apollonov et al 1984;Xiang & Zhang 1985;Lu & Lin 1989;Bao & Jago 2000;Terfelt & Ahlgren 2007;Lazarenko et al 2011).…”

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

“…Agnostoid arthropods are common in the uppermost part of Cambrian Series 3 and in the lowermost Furongian, but generally become rare at higher levels (Terfelt et al 2011;Ahlberg and Terfelt 2012). The succession also yields rare representatives of non-olenid trilobites, referred to as 'invaders' (Conway Morris and Rushton 1988), 'exotics' (Żylińska et al 2004;Weidner and Żylińska 2005;Terfelt and Ahlgren 2007;Weidner 2012, 2013) or 'immigrants' (Terfelt 2006;Terfelt and Ahlgren 2009). Specimens collected over the last 25 years from a number of localities in Sweden (by TW and JA) and glacial erratic boulders in Denmark (by TW) allow a detailed taxonomic study for the first time.…”