Evolutionary ecologists seek to understand how phenotypic evolution relates to population level traits. To document that, we quantified functional traits (escape strategy, sprint speed and predatory performance) and population density across 10 lizard species representing the acquisition of burrowing snake-like morphs (BSLM), from Brazil. We used phylogenetic mixed models to test if: a) morph and substrate affects lizards’ flight strategy and speed, b) BSLM species get more access to different potential prey types than lacertoid ones, when in syntopy, and d) morph is correlated with population abundance and habitat use in a way expected from the output of the previous experiments. We found that BSLM rigidly relied on burrowing as flight strategy, while syntopic lacertoid species changed their strategy according to the substrate. Also, sand has opposite effects on sprint speed depending on morph, making lacertoids run slower and BSLM faster. Despite BSLM were overall slower than lacertoids, they were as good hunters of challengingly fast prey, and better hunters of underground prey. Further, in the sandy habitats where these morphs are syntopic, prey is most available at superficial leaf litter under vegetation, although there is a large stock of underground prey, under the vegetation, too. These results support our observed higher importance of sand for BSLM’s populations and the higher importance of vegetation for lacertoids’ population density. Finally, although BSLM species reached the highest populational densities among the studied species, a systematic effect of morphological evolution on abundance remains elusive.

Abstract Micropaleontology is the study of microscopic fossils such as coccolithophores, foraminifera, diatoms, and radiolaria. These diminutive fossils range in size from 0.001 to 1 mm and are the most abundant and ancient of Earth’s unicellular organisms. I now report the finding of a ~0.5 – 0.6 mm long limbed squamate with a spade-like tail and features that otherwise resemble those of extant Geckos on the dorsal surface of a trace fossil from Hamblen County, Tennessee. Also found are three 0.4 - 0.6 mm long saurian-like juveniles undergoing body elongation and limb reduction, findings in keeping with a lizard-to-snake transformation. The dorsal surface also contains the remains of a tiny snake-like squamate measuring 1.0 mm snout-to-vent and 7.0 mm snout-to-tail. The miniaturization of these fossils may represent an ecomorphological response to the Permian-Triassic and/or the mid-Cretaceous extinctions as well as the metabolic and reproductive advantages of smallness. The findings open a new area of investigation for paleontologists and micropaleontologists and underscore the resilience and variety of life forms on Earth.