Homo erectus is a significant hominid species that lived during the Pleistocene epoch. Fossil evidence supports that they possessed a brain size averaging around 900cc, appeared roughly 1.5 to 1.9 million years ago, and utilized tools to consume a varied, omnivorous diet. Current paleoanthropological consensus generally places H. erectus as a descendant of the earlier H. habilis, making all four statements factually consistent with evolutionary biology.

Archaeopteryx is widely considered a transitional fossil between non-avian dinosaurs and modern birds. It lived during the Late Jurassic period. While it possesses reptilian features like teeth and a long bony tail, it also exhibits avian characteristics such as feathers and wings, marking it as a significant evolutionary link.

The sequence 'Salamander - Python - Kangaroo' represents a progression through vertebrate classes: Amphibia (Salamander), Reptilia (Python), and Mammalia (Kangaroo). This sequence reflects the evolutionary timeline of terrestrial vertebrates moving from water-dependent amphibians to fully terrestrial amniotes (reptiles) and finally to endothermic mammals. Other options mix unrelated groups or invertebrates with vertebrates, making them incorrect in an evolutionary context.

While anatomical features like the opposable thumb are shared with many primates, the advanced cognitive capacity for abstract thought, complex language, and a profound, sustained desire to learn and pass on cultural knowledge is considered a defining human characteristic that separates us from other apes.

Mammoths belong to the family Elephantidae and are closely related to modern elephants. Genetic and morphological evidence confirms that mammoths and modern elephants share a common ancestor, with the mammoth being a distinct genus within the same lineage.

The fossil record provides evidence that life has changed over time. It shows that older rock layers contain simpler, more primitive organisms, while newer layers contain more complex ones. It also demonstrates that species go extinct and are replaced by new forms, and that life has diversified significantly over geological time scales.

The Big Bang theory posits that the universe began as a singularity of infinite density and temperature. As it expanded and cooled, fundamental particles such as protons, neutrons, and electrons formed. While the term 'yelm' is not standard scientific terminology for this singularity, the composition of the early universe post-inflation includes these subatomic particles.

Archaeopteryx exhibits characteristics of both non-avian dinosaurs (reptilian features like teeth, a long bony tail, and claws) and modern birds (avian features like feathers and wings). This makes it a classic example of a transitional fossil that provides evidence for the evolutionary transition from theropod dinosaurs to birds.

The Cambrian Period, beginning approximately 541 million years ago, is famously known for the 'Cambrian Explosion.' This event marks a rapid diversification of life, where most major animal phyla appeared in the fossil record for the first time, representing the first major radiation of complex multicellular organisms on Earth.

Radiometric dating relies on the decay of radioactive isotopes over time. As time passes, the parent isotope decays into daughter products. Therefore, older geological samples contain a lower concentration of the original parent radioactive isotope compared to younger samples.