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Digital SAT Reading: Evolutionary Biology & Fossil Evidence
A high-level Digital SAT Module 2 practice reading text examining recent scientific discoveries that challenge traditional views on early mammalian evolution.
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Recent paleontological findings have challenged the long-held assumption that early mammalian diversification was strictly constrained by the dominance of non-avian dinosaurs. Traditionally, evolutionary biologists hypothesized that Mesozoic mammals were exclusively nocturnal, generalized insectivores occupying narrow ecological niches to avoid direct competition. However, newly discovered eutherian fossils from the Cretaceous period reveal remarkable morphological adaptations, including specialized dentition for frugivory and skeletal structures conducive to fossorial and arboreal locomotion.
These anatomical features indicate that functional differentiation among early mammals was underway well before the Cretaceous-Paleolithic extinction event. Consequently, while the mass extinction undoubtedly precipitated an unprecedented adaptive radiation of surviving lineages, it did not originate mammalian diversity ex nihilo. Instead, it accelerated evolutionary trajectories that were already established, fundamentally reshaping our understanding of Mesozoic ecosystem dynamics.
