. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 162 D. K. A. BARNES 400- >, 300- QJ o 200- c CD O 1 00- 0 -I. M 6SOZOIC Tertiary -200 -150 -100 -50 Years ago ( million ) Figure 1. Global generic diversity of cyclostome and cheilostome bryozoans (combined clades) from late Triassic to Holocene times. Data from Taylor (1993) and IvtcKinney i-t ul. (1998) based on boundaries designated by Harland ct al. (1990). The K-T boundary is shown as a vertical dashed line. those with a high skeletal investment—sedentary lithophyl- lic encrusters ( bryozoans) foremost among the
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 162 D. K. A. BARNES 400- >, 300- QJ o 200- c CD O 1 00- 0 -I. M 6SOZOIC Tertiary -200 -150 -100 -50 Years ago ( million ) Figure 1. Global generic diversity of cyclostome and cheilostome bryozoans (combined clades) from late Triassic to Holocene times. Data from Taylor (1993) and IvtcKinney i-t ul. (1998) based on boundaries designated by Harland ct al. (1990). The K-T boundary is shown as a vertical dashed line. those with a high skeletal investment—sedentary lithophyl- lic encrusters ( bryozoans) foremost among them. Clades that are preserved in this way—that are diverse, abundant, extensive in the fossil record, and extant—offer us the opportunity to apply geological, biological, mathe- matical, fluid dynamic, and chemical (, multidisci- plinary) approaches to understanding the processes under- lying persistence. Cyclostome and cheilostome marine bryozoans, two clades with such attributes, have co-occurred in similar environments for 150 million years. After a long period of gradual taxonomic increase, they underwent a rapid but punctuated increase in diversity during the Late Cretaceous (Fig. 1). Paleontologists and ecologists have studied these bryozoans extensively, and recent information has clarified the interpretation of scale, pattern, and process in their comparative ecology and evolution. In this manuscript, I examine how two competitor clades have managed to per- sist alongside one another for more than 100 million years. As background, I first describe the historical patterns of abundance and taxon richness in these bryozoan clades. Geological Scale and Pattern of Persistence Cyclostome and cheilostome bryozoans occur together in most benthic lithophyllic assemblages, across latitudinal and longitudinal spectra, and frequently in direct competi- tion for space and food (, Sebens. 1986; Lopez Gappa, 1989; Barnes and Dick, 2000). The older of the two clades, the c
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
