Viola Group (Ordovician, Oklahoma) cryptolithinid trilobites: biogeography and taxonomy

Shaw, Frederick

doi:10.1017/s0022336000033242

Cited by 12 publications

(21 citation statements)

References 20 publications

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“…Pope and Steffen (2003) noted that Upper Ordovician carbonates from the southern and western margins of Laurentia contained abundant chert and phosphate, which they interpreted as evidence of widespread upwelling and vigorous thermohaline circulation related to early Gondwanan glaciation. They also point out that this period of upwelling corresponded with cool surface waters in the Appalachian Basin (Railsback et al, 1990), a northward expansion of cool-water trilobite faunas in North America (Shaw, 1991), and a transition to cooler water benthic faunas across eastern North America (Patzkowsky and Holland, 1993). Finally, several workers claimed that Katian (middle to upper Caradoc) siliciclastic deposits in northwestern Gondwana display clear evidence of glacial transport and deposition (e.g., Barnes, 1986;Theron, 1994;Hamoumi, 1999).…”

Section: Paleoenvironmental Controls On Graptolite Diversitymentioning

confidence: 96%

Paleogeographic, paleoceanographic, and tectonic controls on early Late Ordovician graptolite diversity patterns

Goldman¹,

Wu²

2010

The Ordovician Earth System

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The Katian Age (early Late Ordovician) was a time of signifi cant decline in marine biodiversity, but whether this decline was a real phenomenon or an artifact of the relatively few studies devoted to this interval requires further research. We examined the pattern of graptolite faunal changes across the boundary between the Climacograptus bicornis and Diplacanthograptus caudatus graptolite zones in North America and on several other continents. A sharp decline in species diversity occurs in the Appalachian Basin. Scores for normalized diversity dropped from 20 in the C. bicornis Zone to 7 in the D. caudatus Zone. Only 11% of the species present in the C. bicornis Zone carry over into the D. caudatus Zone. A similar pattern occurs in central Oklahoma. Regions at higher paleolatitude, such as Wales and Baltoscandia, exhibit low graptolite diversity in lower Katian strata, and then diversity declines further in higher strata. In other regions at low paleolatitude, such as Australasia and Scotland, however, diversity is fairly constant across this interval (although the percentage of carryover taxa remains low). We conclude that seawater temperature change or disruption of the oceanic density structure, which might accompany temperature change, provides explanations for the similarity between Laurentian and higher paleolatitude diversity patterns. Flooding of the Laurentian craton through the Sebree Trough by cool, subpolar Iapetus seawater may have adversely affected graptolite diversity there. Regions at high paleolatitudes likely underwent cooling associated with Katian climate deterioration. Thus seawater cooling, albeit driven by different mechanisms, may have produced similar diversity patterns at different paleolatitudes. †

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Section: Paleoenvironmental Controls On Graptolite Diversitymentioning

confidence: 96%

Paleogeographic, paleoceanographic, and tectonic controls on early Late Ordovician graptolite diversity patterns

Goldman¹,

Wu²

2010

The Ordovician Earth System

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“…The biotic overturn was accomplished primarily through immigration of extra-basinal taxa into a region following regional generic extinction [2]. For example, trilobites and some brachiopods interpreted as adapted to cooler water conditions participated in northward biogeographic expansion in associated with the spread of temperate carbonates [11,12]. …”

Section: Introductionmentioning

confidence: 99%

Geologic Drivers of Late Ordovician Faunal Change in Laurentia: Investigating Links between Tectonics, Speciation, and Biotic Invasions

Wright

Stigall

2013

PLoS ONE

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Geologic process, including tectonics and global climate change, profoundly impact the evolution of life because they have the propensity to facilitate episodes of biogeographic differentiation and influence patterns of speciation. We investigate causal links between a dramatic faunal turnover and two dominant geologic processes operating within Laurentia during the Late Ordovician: the Taconian Orogeny and GICE related global cooling. We utilize a novel approach for elucidating the relationship between biotic and geologic changes using a time-stratigraphic, species-level evolutionary framework for articulated brachiopods from North America. Phylogenetic biogeographic analyses indicate a fundamental shift in speciation mode—from a vicariance to dispersal dominated macroevolutionary regime—across the boundary between the Sandbian to Katian Stages. This boundary also corresponds to the onset of renewed intensification of tectonic activity and mountain building, the development of an upwelling zone that introduced cool, nutrient-rich waters into the epieric seas of eastern Laurentia, and the GICE isotopic excursion. The synchronicity of these dramatic geologic, oceanographic, and macroevolutionary changes supports the influence of geologic events on biological evolution. Together, the renewed tectonic activity and oceanographic changes facilitated fundamental changes in habitat structure in eastern North America that reduced opportunities for isolation and vicariance. They also facilitated regional biotic dispersal of taxa that led to the subsequent establishment of extrabasinal (=invasive) species and may have led to a suppression of speciation within Laurentian faunas. Phylogenetic biogeographic analysis further indicates that the Richmondian Invasion was a multidirectional regional invasion event that involved taxa immigrating into the Cincinnati region from basins located near the continental margins and within the continental interior.

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“…One of the characteristic features of the group is the presence of a bilamellar cephalic fringe bearing an array of funnel-shaped pits of presumed sensory function (see Chatterton 1980;Shaw 1991); however, Fortey and Owens (1999) suggested that the fringe pits were associated with ®lter feeding. These pits are commonly arranged in concentric arcs and radial rows.…”

Section: O R P H O L O G Ymentioning

confidence: 99%

The taxonomy and stratigraphical significance of the Anglo–Welsh Cryptolithinae (Trinucleidae, Trilobita)

Bowdler-Hicks¹,

Ingham²,

Owen³

2002

Palaeontology

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ABSTRACT. The taxonomic status of the stratigraphically-important Caradoc genera Salterolithus Bancroft, 1929, Broeggerolithus Lamont, 1935 and Smeathenia Dean, 1960 and the species therein is critically reviewed. The radial alignment patterns of the fringe pits within the E arcs are used to distinguish Salterolithus from Broeggerolithus; fringe morphology and pit counts are used to distinguish species within these genera.`Broeggerolithus' harnagensis is reassigned to Salterolithus and S. praecursor, S. caractaci paucus and Smeathenia smeathenensis are all regarded as junior synonyms of Salterolithus harnagensis. This revision of the Anglo-Welsh Cryptolithinae reveals the evolution of morphologically very variable populations and environmentally constrained morphotypes and species. Eight species and subspecies of Salterolithus and Broeggerolithus are retained and redescribed and their stratigraphical distribution in the Caradoc of Britain, Ireland, Belgium and Scandinavia is clari®ed.

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Viola Group (Ordovician, Oklahoma) cryptolithinid trilobites: biogeography and taxonomy

Cited by 12 publications

References 20 publications

Paleogeographic, paleoceanographic, and tectonic controls on early Late Ordovician graptolite diversity patterns

Paleogeographic, paleoceanographic, and tectonic controls on early Late Ordovician graptolite diversity patterns

Geologic Drivers of Late Ordovician Faunal Change in Laurentia: Investigating Links between Tectonics, Speciation, and Biotic Invasions

The taxonomy and stratigraphical significance of the Anglo–Welsh Cryptolithinae (Trinucleidae, Trilobita)

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