Creationism, Evolution, & Origin Stories: Fossil Record

Distinguished evolutionary biologists among the auditors of the foregoing lectures take on not only Luther Sutherland (who remains unconvinced by what they consider the obvious truth but is unable to convince them of the truth that is obvious to him), but one another as well—proving that Darwin’s theory of evolution is itself still evolving. (26 minutes)

Starting from the Biblical description of the Flood, this presentation is an overview of six easily-grasped, convincing, large-scale evidences for the Flood. Visit examples of fossils and rock layers from the Grand Canyon that can be found across the North American continent and beyond.

This program presents fossil evidence for the evolution of reptiles and amphibians; explains the reasoning processes scientists must use when no direct evidence is available for examination; illustrates field techniques for collecting fragile fossils for transportation to the laboratory, where examination can take place under controlled conditions; and traces the evolution of some modern mammals back through time. After viewing the program, students should know which major features distinguish amphibians from reptiles, when and for how long reptiles were the dominant land animals and by whom they were replaced, and recognize the feature in the fossil remains of land reptiles that may indicate that they gave rise to mammals. (20 minutes)

Fossilization typically occurs when organisms (either living or dead) are deposited from water into sediment. In some instances the sediment solidifies, making a cast of the entombed organism; in others, the organic material of the organism itself is replaced by mineral to form a stony replica.

Paullinieae are a diverse group of tropical and subtropical climbing plants that belong to the soapberry family (Sapindaceae). The six genera in this tribe make up approximately one-quarter of the species in the family, but a sparse fossil record limits our understanding of their diversification. Here, we provide the first description of anatomically preserved fossils of Paullinieae and we re-evaluate other macrofossils that have been attributed to the tribe. We identified permineralized fossil roots in collections from the lower Miocene Cucaracha Formation where it was exposed along the Culebra Cut of the Panama Canal. We prepared the fossils using the cellulose acetate peel technique and compared the anatomy with that of extant Paullinieae. The fossil roots preserve a combination of characters found only in Paullinieae, including peripheral secondary vascular strands, vessel dimorphism, alternate intervessel pitting with coalescent apertures, heterocellular rays, and axial parenchyma strands of 2-4 cells, often with prismatic crystals. We also searched the paleontological literature for other occurrences of the tribe. We re-evaluated leaf fossils from western North America that have been assigned to extant genera in the tribe by comparing their morphology to herbarium specimens and cleared leaves. The fossil leaves that were assigned to Cardiospermum and Serjania from the Paleogene of western North America are likely Sapindaceae; however, they lack diagnostic characters necessary for inclusion in Paullinieae and should be excluded from those genera. Therefore, the fossils described here as Ampelorhiza heteroxylon gen. et sp. nov. are the oldest macrofossil evidence of Paullinieae. They provide direct evidence of the development of a vascular cambial variant associated with the climbing habit in Sapindaceae and provide strong evidence of the diversification of crown-group Paullinieae in the tropics by 18.5-19 million years ago.

Solanaceae is a large cosmopolitan family of angiosperms that includes some 92–100 genera and 2300–2500 species. It has been the object of a great deal of attention because of its economic importance as a food source (tomatoes, potatoes, peppers), because it includes tobacco, and is source of drugs (alkaloids). However its fossil history has been elusive with relatively few seemingly reliable reports throughout Tertiary times and no solid bases for molecular dating models to pinpoint important events in its diversification and evolution. While the great diversity found within the family makes it difficult to find morphological characters that define it, in general, the flowers have an overall distinctive morphology with some diagnostic morphological characters. Thus, as is often the case, flowers are potentially the most reliable indicators of the family in the fossil record. There have been a number of reports of flowers representing Solanaceae in the Tertiary. Yet, we report here that upon reinvestigation only one taxon remains as a plausible representative of the family while one of the most notable and frequently cited fossil Solanaceae from the Tertiary of North America is clearly a member of the family Rhamnaceae consistent with the fossil leaf record.

Inference of past and present global biodiversity requires enough global data to distinguish biological pattern from sampling artifact. Pertinently, many studies have exposed correlated relationships between richness and sampling in the fossil record, and methods to circumvent these biases have been proposed. Yet, these studies often ignore paleobiogeography, which is undeniably a critical component of ancient global diversity. Alarmingly, our global analysis of 481,613 marine fossils spread throughout the Phanerozoic reveals that where localities are and how intensively they have been sampled almost completely determines empirical spatial patterns of richness, suggesting no separation of biological pattern from sampling pattern. To overcome this, we analyze diversity using occurrence records drawn from two discrete paleolatitudinal bands which cover the bulk of the fossil data. After correcting the data for sampling bias, we find that these two bands have similar patterns of richness despite markedly different spatial coverage. Our findings suggest that i) long-term diversity trends result from large-scale tectonic evolution of the planet, ii) short-term diversity trends are region-specific, and iii) paleodiversity studies must constrain their analyses to well-sampled regions to uncover patterns not driven by sampling.