Carr, R. K., 1995a. - Biological Sciences
Carr, R. K., 1995a. - Biological Sciences
Carr, R. K., 1995a. - Biological Sciences
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
-87<br />
IG inferognathal plate, injerognathale;<br />
MD median dorsal plate, plaque mediane dorsale;<br />
Mk Meckel's cartilage, cartilage de Meckel;<br />
PVL posterior ventrolateral plate, plaque ventrolaterale posterieure;<br />
Qu quadrate ossification of the palatoquadrate, ossification carree du palatocarre;<br />
SO suborbital plate, plaque suborbitaire;<br />
scler sclerotic plate, anneaux sclerotiques.<br />
MATERIAL AND METHODS<br />
Appendix I provides a species level compilation of stratigraphic ranges for all placoderms<br />
(DENISON, 1978; placoderm references from the Zoological Record, 1975-1991). It includes taxonomically<br />
and temporally ambiguous taxa (e.g. indeterminate material, unresolved synonyms,<br />
species based on fragmentary material, incerfae sedis). Indeterminate taxa are included whenever<br />
they provide temporal range information or represent forms from distinct geographic regions.<br />
Temporal resolution for taxa ranges from indeterminate to substage (50 species without stratigraphic<br />
resolution to series are recorded in Appendix I, but are not included in diversity analyses).<br />
A range through method is used for taxa with poor stratigraphic resolution (e.g. a Frasnian occurrence<br />
is recorded as a Lower to Upper Frasnian presence at the substage level). Also included<br />
is unpublished data from research in progress (indicated in Appendix I as "n. sp.", CARR &<br />
HLAVIN, in press, Dunkleosteus n. sp. 1, D. n. sp. 2; CARR, MS, Stenosteus n. sp. -pers. comm.<br />
LELIEVRE, Maideriajalipoui, this volume). A total of 720 taxa are recorded with diversity patterns<br />
(number of taxa per unit of time) analyzed at different levels of temporal and taxonomic resolution<br />
(among the 720 taxa there are 267 recognized genera and 591 recognized species. Thirty-three<br />
forms are indeterminate to a generic level with an additional 41 species having questionable<br />
assignments to generic level. Seventy-five taxa assigned to a genus lack assignment of a species<br />
name; recorded as "sp.". Eight taxa represent species provisionally assignable to other recognized<br />
species; recorded as "cf.". One conferrable genus is recorded. Seven questionable species assignments<br />
are recorded with one specific variety noted.). Extinction levels for the Frasnian<br />
Famennian boundary are recorded for both species- and genus-levels and at stage- and<br />
substage-levels of analysis (table]).<br />
It is important to consider the level and units of anillysis to be used in the study of diversity.<br />
Placoderm data suggest substage-level analyses are necessary to clearly evaluate subclade patterns.<br />
The resolution of the individual data is less critical; however, this may be due solely to<br />
the relatively low level of indeterminate taxa (4.6% indeterminate to genus and 5.7% with<br />
questionable generic assignments) and taxa with poor stratigraphic resolution (6.8% not resolved<br />
to series (epoch) and 11.9% resolved to series). Stage names follow those of DENISON (1978)<br />
which are used in his compendium. No effort has been made to convert DENISON'S Early Devonian<br />
stage names (Gedinnian and Siegenian) to current formal names (Lochkovian and Pragian) since<br />
exact stratigraphic data is not available for an accurate conversion (refer to HARLAND et aI.,<br />
1989, for a discussion of the relationship between formal names and those used by DENISON,<br />
1978). Stage names for the last appearance data taken from SEPKOSKI (1992) follow those of<br />
HARLAND et al. (1989).