The asaphid trilobite fauna: Its rise and fall in Baltica

Pärnaste, Helje; Bergström, Johan

doi:10.1016/j.palaeo.2013.06.007

Cited by 11 publications

(1 citation statement)

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“…Among the early representatives of the Asaphidae, Asaphellus Callaway, 1877 is an important genus in helping to resolve the diversification of the family, and as currently conceived is remarkly rich in species, with nearly 70 (e.g., Harrington 1938;Harrington & Leanza 1957;Courtessole et al 1985;Zhou & Zhang 1985;Fortey & Owens 1987, 1991, 1992Peng 1990;Vidal 1998). Moreover, Asaphellus is also one of the earliest asaphids with a worldwide distribution, whereas most early genera such as Golasaphus Shergold, 1971, Griphasaphus Öpik, 1967, Norinia Troedsson, 1937 were geographically restricted (Pärnaste & Bergström 2013). Asaphellus is also particularly interesting due to its long stratigraphic range, originating in the Furongian and persisting until the Darriwilian (Fortey & Owens 1987).…”

Section: Introductionmentioning

confidence: 99%

Diversification ofAsaphellusCallaway, 1877 (Asaphidae: Trilobita) during the Tremadocian in South West Gondwana (Cordillera Oriental, Argentina)

2015

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Asaphellus Callaway, 1877 is the earliest widespread genus of the family Asaphidae Burmeister, 1843, and although its systematics bears several problematic issues, an input to overcome these difficulties has been attempted. Our main focus is a group of strongly effaced Asaphellus species from the Cordillera Oriental (NW Argentina), including new material from the Santa Rosita Formation (Furongian-Tremadocian), mainly belonging to Alfarcito and Rupasca members (Quebrada del Arenal, Perchel, Jujuy Province). Asaphellus is reconsidered herein in order to restrict some features and discuss others not taken in account before. Moreover, several problematic Argentinean species are revised. The poorly known, but extensively cited, A. catamarcensis Kobayashi, 1935 is assessed here upon the type series in order to clarify its taxonomy and previous assignments. A reappraisal of A. stenorhachis (Harrington, 1938), another enduring problematic taxon, is proposed. Besides, A. isabelae n. sp., a unique species within the genus mainly due to its extreme effacement is defined herein. Other species left in open nomenclature are also described. Regarding local random occurrences in the Furongian, the genus radiated locally from the early Tremadocian (Tr1) onwards, however, taxonomic diversification was not mirrored by the abundance of Asaphellus in local communities. From the middle Tremadocian (Tr2) this diversification is associated with an increase in abundance, and even dominance of the taxon in numerous assemblages, further expanding its environmental range into shallower settings. The increase of Asaphellus diversity (Tr1-early Tr2) is decoupled from the records of local increase in Asaphidae diversity since the late Tremadocian (Tr3) and Floian, underscoring the complex pattern of diversification at different taxonomic levels.

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Section: Introductionmentioning

confidence: 99%