Page 221 - Introduction to Paleobiology and The Fossil Record

208 INTRODUCTION TO PALEOBIOLOGY AND THE FOSSIL RECORD

calcareous Plankton
phosphatic
siliceous Globigerinine foraminiferans
agglutinated Calcareous nanoplankton
organic-walled
Acritarchs Dinoflagellates Radiolarians Diatoms Silicoflagellates foraminiferans
Benthic
0 Neogene }
Ceno- zoic Paleogene Tintinnids

100 Cretaceous
Mesozoic Jurassic

200 Chitinozoans Conodonts
Triassic
Rotaliina
Permian
300 Carboniferous
Age (Ma) Devonian Lagenina

400 Paleozoic Silurian Miliolina
Fusulinina
Ordovician

500
Cambrian Ostracoda
Ediacaran
Neoproterozoic Cryogenian
600 Allogromiina Textulariina

700
Figure 9.2 Stratigraphic ranges of the main protist groups. (From Armstrong & Brasier 2005.)

bonates of the Hunting Formation, eastern the later Proterozoic, anticipating more modern
Canada, dated at 1.2 Ga (see p. 200). After oceanic biological and chemical systems.
1 Ga, algae are reported from a range of locali-
ties around the world. A range of protists such
as the acritarchs, chitinozoans, coccolitho- PROTOZOA
phores and diatoms dominated the phyto- Protozoans are neither animal nor plant, but
plankton at various stages from the Late single-celled eukaryotes that commonly show
Precambrian to the present, whereas the fora- animal characteristics such as motility and
miniferans and radiolarians were important heterotrophy; some groups are able to form
parts of the zooplankton (Fig. 9.2). Apart from cysts. Most are about 50–100 μm in size and
a role as a primary food source, the marine are very common in aquatic environments
phytoplankton function as a major carbon and in the soil. They can occupy various levels
sink, initially removing CO 2 from the atmo- in the food chain ranging from primary pro-
sphere as carbonate ions. These cycles may ducers to predators and some groups function
already have been in place throughout much of as parasites and symbionts.