When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

A hundred years ago, Anomalocaris canadensis Whiteaves, 1892, was described as the body of a Phyllopod Crustacean. At NAPC III in Montreal in 1982, Whittington and Briggs showed that Anomalocaris canadensis was a claw, one of a pair at the front of an extraordinary predatory animal, whose jaws had previously been described as a jellyfish (Peytoia). The search to understand Anomalocaris and its relatives continues. So does the mistaken allocation of separated parts.

In 1991, the first complete Anomalocaris canadensis was collected. It has a fan tail, much like the tail of another Burgess Shale conundrum, Opabinia. Another new specimen shows that its head and claws were more flexible than previously realized, and its eyes were on stalks.

The large feeding claw, Appendage F, was allocated first to the arthropod, Sidneyia, by Walcott, then to the other Anomalocaris species, A. nathorsti, by Whittington and Briggs. The small size and lack of strong cross spines on the claws of A. nathorsti suggest that Appendage F probably came from another anomalocarid. Another puzzling feature on A. nathorsti is the thin, segmented structure running across the abdomen, one per body segment, ending in a club-shaped extremity on each side.

A third anomalocarid is now recognized in the Burgess Shale. Its front half is composed of 3 or 4 carapace like parts previously named Hurdia and Proboscicaris. Two small sheathed claws on stalks are attached at the rear of the “carapaces”. Hanging below the rear of the “carapaces” is a grasping, feeding organ composed of a pair of claws and Peytoia jaws with an inner set of teeth. It is connected to the body which has 11 segments and a tail. The two “oblique compressions” and the Peytoia jaws with the extra group of “spines” within the mouth allocated by Whittington and Briggs (1985) to Anomalocaris nathorsti almost certainly belong to the Hurdia anomalocarid.

It is evident that attempting to allocate anomalocarid parts to a particular anomalocarid is much like a Pin-the-Tail-on-the-Donkey game. In both cases the players are operating in the dark. The differences are that there is an unknown number of anomalocarids in the Burgess Shale and not only do they disarticulate easily, but they often have similar parts. As a consequence, our understanding of the anomalocarids is almost completely dependent on finding articulated specimens with the parts in place. This in turn depends on the success of field excavation. It took 100 years and 12 seasons of excavation to get the first complete Anomalocaris canadensis.

Edrioasteroids are an extinct group of primitive echinoderms whose geologic range is Early Cambrian to Late Pennsylvanian. Several authors have argued whether edrioasteroids could freely move about on the sea floor or were firmly attached to a hard substrate throughout post-larval life. Arguments that edrioasteroids were mobile are based primarily on orientation of individuals within a population and positioning of individuals on a host shell. We disagree with these arguments based on overwhelming evidence that edrioasteroids could not move and remained firmly attached throughout post-larval life.

Edrioasteroids have specialized attachment structures that are almost always found on hard substrates such as hardgrounds, fossil shells or fragments, and conglomerate pebbles. There are two types of edrioasteroid attachment structures, an aboral disk and a peripheral rim. Edrioasteroids with an aboral disk are typically found attached to hard substrates. Although some individuals have been found loose in muddy sediment, many of these individuals show signs of being torn loose from their attachment surface based on their inverted orientation, disrupted attachment structures, and shingling by currents. Edrioasteroids with a peripheral rim are almost never found free in the sediment, and the few known examples of this are either small juveniles indicating that soft substrates probably could not support adult edrioasteroids or else thick-rimmed adults apparently attached to soft algae.

In uncrowded conditions, edrioasteroids are circular in outline, but they become polygonal and abutting under crowded conditions. Other encrusters such as tube worms also affect their peripheral outline. Edrioasteroids occur in crowded clumps even though nearby skeletal grains are uncolonized. In these individuals, peripheral rims and oral surfaces are severely distorted which would make living conditions and continued growth difficult. Also, some individuals attach to objects much smaller than their eventual thecal diameter. In such conditions, the edrioasteroid gradually engulfs the object it is attached to, severely distorting the animal, with the peripheral rim migrating toward the bottom of the attachment object. Under either of these conditions, individuals would almost certainly have moved to nearby open spots or to larger, uncolonized clasts if they could.

In crowded conditions, individuals of the same species do not overgrow one another, but individuals of one species will overgrow living individuals of another species competing for the same attachment space. Two localities preserve large edrioasteroids partially overgrowing smaller articulated individuals of a different species. Because they are fully articulated, overgrown individuals must have been alive during the overgrowth, but were not able to move out of the way.

Disrupted edrioasteroids are often found with the oral surface completely disarticulated or missing, but with a completely articulated peripheral rim. Apparently, the peripheral rim was firmly attached to the substrate and more strongly constructed than the oral surface and therefore better able to withstand wave activity, death and decay, and subsequent disarticulation than the oral surface. This firm attachment to hard substrates also suggests lack of movement.

The edrioasteroid attachment grows from the periphery. New ossicles are added to distal plate circlets of the attachment while plates in more proximal circlets enlarge. Clearly some degree of movement is required for this type of growth but not active locomotion. Large edrioasteroids growing along the margin of a large skeletal fragment show an underdevelopment of the peripheral rim along this edge even though the rest of the animal is round and symmetrical.

Some authors have used living psolid holothurians as a good analog for extinct edrioasteroids with a peripheral rim. Psolids will move using tube feet under the theca in the ventrally positioned A, B, and E rays under extreme disturbance, but only at the rate of a few millimeters per day. Edrioasteroids have all the ambulacra dorsally oriented away from the substrate and therefore have no similar mechanism for locomotion. We suggest balanimorph barnacles as a better analog for the vast majority of edrioasteroids. They firmly attach to a hard substrate, become polygonal in crowded conditions, have feeding structures facing upward, grow from the periphery of the attachment surface, and do not move as adults.

Modern understanding of skeletal microstructure in fossil corals builds on knowledge of structure and biomineralization in modern corals and diagenesis of carbonate skeletons. It is agreed that the skeleton of living stony corals, the Scleractinia, is made of fibrous aragonite, with growth of biocrystals generally according to rules of crystal growth as observed in inorganic aragonite, but here controlled by organic matrix. Fossil scleractinians all apparently fit the same model of biomineralization seen in living corals, although some early taxa (Triassic) lack septal trabeculae, rod-like framework structures typical of all living and most fossil septate corals.

Paleozoic corals, both septate Rugosa and non-septate Tabulata, had a skeleton of calcite, most likely low-magnesium calcite, thus had diagenetic histories differing considerably from the aragonitic Scleractinia. Agreement is lacking as to whether a single structural motif can be defined for the calcitic corals, that is, whether the Rugosa and Tabulata originally had a calcitic skeleton built of fibrous biocrystals, analogous to the scleractinians, or whether some others originally had a non-fibrous, lamellar skeletal microstructure. The disagreement hinges on whether both of these basic configurations are biogenic, or whether the latter is sometimes or always diagenetic in origin. The presence of matrix control over biomineralization in Rugosa and Tabulata is yet to be proven, but will play an important role in models for biocrystallization in these older cnidarians. Details of diagenetic history and modification of structures in these calcitic corals likewise warrant investigation to improve our ability to interpret the Paleozoic corals.

Biogeographic patterns from early Cambrian trilobites are used to evaluate the nature and timing of the Cambrian radiation. Results from a phylogenetic biogeographic analysis reveal that patterns of vicariance are compatible with a vicariant distribution of trilobites across what were originally joined elements of the supercontinent Pannotia; further, there is limited evidence for coordinated range expansion or geo-dispersal by these trilobites. As Pannotia had split apart sometime between 550-600 Ma this suggests that trilobites, and by extension several other metazoan taxa, had begun to diversify by this interval. This result suggests that there may have been some period of cryptic diversification by metazoans prior to the Cambrian radiation, though the inferred length of this interval is not as long as that invoked by some molecular studies. Perhaps trilobites existed at low population densities in marginal environments before they became paleontologically emergent. Even though the results suggest some apparent gap in the fossil record, the evolutionary signature of this gap is still preserved in the paleobiological patterns from the fossil record, indicating that the fossil record is still the one best source of data on the nature of key episodes in the history of life, like the Cambrian radiation.

One of the most salient advances in vertebrate paleontology in recent decades has been the settling of the question of the origin of birds, a problem that has vexed evolutionary biologists since well before Darwin. To be sure, the consensus is not unanimous, and many details of this branch of the phylogenetic tree are yet to be worked out, but we now have a much clearer picture of this problem than we had a decade ago. Less settled, but equally stimulating, has been the controversy over the origin of flight in birds and other flying vertebrates. Was there a gliding stage? Did flight begin from the ground up or from the trees down? Were birds initially arboreal? What selective pressures drove the ancestors of birds to take advantage of the aerial opportunity?

Evolution is the great synthesizing principle of biology and cosmology that our students deserve to know in order to understand their world most fully. Yet evolution has social Darwinism as its dark side. An evolutionism or a scientism that teaches in the name of science that there is no God, there is no soul, there is no ultimate purpose in life, and there is no such thing as free will is not the friend of society. Creationists reject evolution not in ignorance of modern science but because of the anxieties it brings. While 90% of Americans profess to believe in God, less than half the population believes in some form of evolution. Science discounts human experience, while religion is about human experience. When forced to choose between a religion that enriches human experience and an evolutionary science that ignores human experience and minimizes humans as a species, people will unhesitatingly choose the religion that gives meaning to their daily struggles. That choice is not a necessary one, but so long as the most visible public spokespersons for evolution pursue their metaphysical agenda, people will continue to choose religion.

Over two hundred years ago the Swedish scientist Carl Linnæus (1781), in an analysis of the biogeographic patterns of living organisms, suggested that all species originated in Paradise. Although there has been considerable progress in the understanding of biogeographical patterns during the intervening two centuries, modern debate has focused on the general applicability of the concept of faunal realms together with the relevance of dispersal, panbiogeographic, and vicariance models (Nelson and Platnick, 1981). To date, studies of Paleozoic brachiopod biogeography have no strong theoretical base; rather the various numerical techniques available, including both cladistic and phenetic methodologies, have helped organize the growing amount of distributional data into recognizable and useful structures.

Ecology is the study of the relationships between organisms and their environments. For brachiopods living in marine habitats the main external factors of interest are temperature, water chemistry, light characteristics, and oxygen availability. However, organisms also modify their environments and in many cases the biotic environment may dictate changes or organism responses. Factors of importance here for animals are resources consumed (usually food items), predators that consume the species under study, organisms that compete for resources, organisms that provide benefits such as symbiotic arrangements or new habitat for colonisation, and those organisms which reduce the quality of the environment such as pathogens or parasites.

The evidence available for determining time resolution in plant fossil deposits can be subdivided easily into two general categories: the information provided by the biological properties of the plants and the information provided by the physical properties of the sediments and accumulation styles. Accordingly, this contribution is divided into two sections, covering these two aspects of time resolution from modern plant accumulations. From a standpoint of modern macrofloral accumulation, there are four ideas that have guided this chapter.

The Late Neoproterozoic or Ediacaran biota contains a variety of enigmatic fossils of uncertain, but likely metazoan, affinities. The protistan group Choanoflagellata and Metazoa share a common ancestor predating the first fossils by perhaps 100's of millions of years. Sponge choanocytes closely resemble choanoflagellates, establishing a morphologic similarity as well. Fossils in the late Neoproterozoic may represent stem or early groups of cnidarians, while others resemble eumetazoans and bilaterians. These organisms occurred on all continents except Antarctica, and occupied four major habitats from prodeltaic to deep slope environments in each area. Their paleoecology was complex but similar to modern soft-bodied slope organisms. Ediacaran trophic structures were complex as well and included a wide variety of feeding types from detritovores, herbivores on microbial mats, filter-feeders, and predators. Ediacaran assemblages thus constitute the evolutionary and ecological precursors of later Phanerozoic and modern biotas.

Thin-shelled, weakly articulated, epifaunal byssate to free-living flat clams characterize Devonian-Cretaceous dark, organic-rich shale facies. Convergent evolution on the flat-clam morph occurs among several families of Bivalvia. Flat clams regularly occurred in dense populations, dominating low diversity, inequitable communities for which they were commonly the pioneer species and formed shell islands for the colonization of smaller, firm-substrate dependent invertebrates. The unique flat-clam dominated ecosystem, as well as the widespread environments to which they were adapted, disappeared at the end of the Cretaceous. Although locally, low-oxygen benthic muds exist through the Cenozoic to Recent, they do not support large populations of flat clams, whose ecological niche was never filled after the Cretaceous. Flat clams underwent an exponential increase in size and apparent growth rates through the mid- and Late Cretaceous, reaching over 3 m in diameter (Inoceramidae). Most of this increase in shell size also involved expansion of mantle tissue and probably gills, relative to the size of the visceral mass. This suggests specific adaptations to colonization of oxygen-poor benthic habitats with hydrogensulfide enriched substrates, which broadly characterized Paleozoic and Mesozoic epicontinental seas, during greenhouse intervals. Such conditions were particularly well-developed during Cretaceous Oceanic Anoxic Events, at which time flat clams thrived.

Functional morphology, geochemistry, and facies associations suggest that many flat clams were chemosymbiotic and/or had greatly expanded oxygen-absorption surfaces. These adaptations allowed them to be opportunistic in chemically stressed benthic environments; growth rates also seem to be enhanced in these environments, a characteristic of living chemosymbiotic species. Many lines of evidence prove that flat clams lived in these environments and do not represent pseudoplanktic rain. A combination of factors seems to have been responsible for their disappearance near the end of the Cretaceous; i.e., mass extinction, loss of primary habitats, and major radiation among bottom-feeding bivalve predators.

Nobody knows exactly when and where Lady Ichnology was born; but everybody would agree that she is coming of age. There are unmistakable signs of this: social acceptance, for instance, or its own journal, and a progeny that can only be estimated from the yearly flow of publications and from a regular newsletter sent out in numbers that make book publishers greedy.

Specimens of all types and sizes can be molded with room temperature vulcanizing silicone rubber (R.T.V.). Mold making procedures, when using R.T.V., differ little from those followed when molding with latex, polysulfide, or polyurethane rubbers. The most important difference is that when using R.T.V. separators are not, under normal circumstances, required either in the making of the mold or in the production of the cast. This allows for the ultimate in surface detail replication in the cast. Thus R.T.V. compounds are ideal for molding small specimens and portions of larger specimens requiring examination using electron microscopy, typically used in vertebrate paleontology for the examination of micro-striations on teeth (for masticatory functions and dietary studies) or bones (for pathologic and taphonomic examinations).

Taxonomic data analysis has benefited greatly from standardization of systematic and stratigraphic practices. In contrast, the unique features of each group of organisms and the specific nature of many workers' questions have helped make analysis of morphological data relatively less standardized and more idiosyncratic. In addition, paleobiological analysis of morphological data at larger (roughly, suprafamilial) scales seems to have lagged behind analysis, of taxonomic data because of the relative difficulty with which morphological data are collected (both from fossils themselves and from published sources). In this review, I will briefly touch upon some of the areas in which morphological analysis has contributed significantly to our understanding of life's history. Space limitations preclude a thorough treatment of all aspects of morphological analysis, and the decision to omit certain topics, such as functional morphology, is not a reflection of the importance of these fields.