Included in this Chapter are tabulations of data on which are based discussions of Proterozoic and earliest Cambrian carbonaceous remains, trace and body fossils (Chapter 7); the Late Proterozoic–Early Cambrian evolution of metaphytes and metazoans (Chapter 8); and the Proterozoic–Early Cambrian diversification of metazoans and metaphytes (Section 11.4). Specifically, tabulations (including an evaluation of the nature and origin of the taxa and objects listed) are presented below for the following six categories of megascopic remains:

1. (1) Proterozoic and selected Cambrian megascopic carbonaceous films (Table 23.1);

2. (2) described genera and species of Proterozoic and Early Cambrian calcareous algae (Tables 23.2.1–23.2.5);

3. (3) taxonomically described, as well as figured but not formally described, Ediacaran (Table 23.3.1) and other Proterozoic (Table 23.3.2) metazoan body fossils;

4. (4) taxonomically described, as well as figured but not formally described, Proterozoic (Vendian) metazoan trace fossils (Table 23.4);

5. (5) genera of Late Proterozoic–Early Cambrian skeletal fossils (Table 23.5); and

6. (6) Proterozoic and selected Cambrian megascopic dubiofossils and pseudofossils (Table 23.6).

Proterozoic and Selected Cambrian Megascopic Carbonaceous Films

In Table 23.1 are listed, alphabetically and by year of publication, reported Proterozoic and selected Cambrian megascopic films. The conventions noted below have been used in Table 23.1.

Type code: ** = holotype of the type species of the indicated genus; * = holotype of a species other than the type species of the indicated genus.

The fossil record of the later Proterozoic through the Early Cambrian is marked by extraordinary change. This change indicates a fundamental reorganization of the biosphere from the exclusively single-celled prokaryotic and protistan ecosystems that prevailed during much of the Proterozoic, to ecosystems characterized by complex multicellular plants and animals of the latest Proterozoic and Early Cambrian. The first recorded events in this transition took place about 900 Ma and the last about 550 Ma, a period of time exceeding that since the end of the Paleozoic. But the final and most dramatic phase, the “Cambrian Explosion,” occurred over a few tens of Ma at the onset of the Cambrian.

The glaring contrast between the Precambrian and the Phanerozoic has long been recognized as a major problem in the history of life. Darwin (1859) attempted to explain the sudden appearance of the Cambrian fauna by inadequacies of the rock record, and Walcott (1910) used a similar concept in his “Lipalian Interval” at the base of the Cambrian. Certainly the abrupt appearance in some local areas (for example, in the contact between Yudomian dolomites and Tommotian limestones in the Aldan-Lena region of Yakutia; Rozanov et al. 1969; Khomentovskij and Karlova 1986) may still be explained by incompleteness of the record.

This Chapter deals with the records of all of the Proterozoic fossil finds which are not included among the prokaryotic or protistan fossils dealt with in Chapter 5. In general, therefore, Chapter 7 deals with the earliest fossil records of higher organisms on earth. However, where systematic assignment is subject to debate there is unavoidable overlap with the prokaryotes and protists.

In historical perspective, publications describing presumed Precambrian megafossils of various kinds go back more than 100 years. Reports of carbonaceous films appeared as early as 1854 (Eichwald 1854). “Trace fossil” descriptions date from 1866 (Dawson 1866), and “body fossils” from 1872 (Billings 1872a, b). Related to the now-famous Ediacaran faunas, the first unequivocal megafossil to be described was that of Rangea schneiderhöhni reported by G. Gürich in 1930 from rocks in southwest Africa. Since these early reports, hundreds of widely, if not universally accepted Proterozoic megafossils have been described from around the world. This record of Proterozoic megafossil remains is therefore not without its share of problems which are similar to those associated with the phylogenetically lower organisms described in Chapter 5. These problems include decisions regarding biogenicity and fossil syngenicity, as well as doubts about geologic age. There are disparate taxonomic judgments, including the differing environmental and/or evolutionary interpretations such judgments may engender. In some instances the reasoning may be circular.