. Bulletins of American paleontology. 172 Bulletin 357 ? Encrusting ? Erect H Free-living. 300 15 10 5 Time interval (Ma) Text-figure 13.—Temporal distribution of numbers (A) and per- cent (B) of species of three growth forms in PPP and DR collections combined. Collections are "binned"' in intervals as in Text- figure 2. or fewer collections (, fewer than 2% of the 328 PPP and DR collections). Only two encrusting species, Tremogasterina mitcronata and Biflustra savartii, are among the 20 most abundant species in the combined dataset, and both are present in both the PPP an
. Bulletins of American paleontology. 172 Bulletin 357 ? Encrusting ? Erect H Free-living. 300 15 10 5 Time interval (Ma) Text-figure 13.—Temporal distribution of numbers (A) and per- cent (B) of species of three growth forms in PPP and DR collections combined. Collections are "binned"' in intervals as in Text- figure 2. or fewer collections (, fewer than 2% of the 328 PPP and DR collections). Only two encrusting species, Tremogasterina mitcronata and Biflustra savartii, are among the 20 most abundant species in the combined dataset, and both are present in both the PPP and the DR collections (Table 3). In marked contrast, free-liv- ing species show "flat" frequency curves, , with equal numbers of species having few and many oc- currences (Text-fig. 12). The curves for erect species are intermediate in pattern, distinctly less hollow than those for encrusting ones (Text-fig. 12). Only two erect species, Nellia tenella and Thalamoporella biperfora- ta, both present in both the PPP and DR collections, are ainong the top ten in abundance in the combined dataset (Table 3). Frequency curves for the same growth form are strikingly similar between the PPP and DR collections (Text-fig. 12), suggesting that these are inherent prop- erties of species having these growth forms rather than effects of environmental or preservational differences between the two areas. Frequency curves plotted against abundance (not shown) are very similar to those plotted against occurrences (Text-fig. 12), be- (0 c o o (1) ^ 200 o "35 o c <T3 T3 C < 100 - ? Encrusting ? Erect H Free-living. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Paleontological Research Institution (Ithaca, N. Y. ); Columbia University. Ithaca, N. Y. , Paleontological Research Institution [etc. ]
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