Pablo Aragonés

University of Alberta | UAlberta · Department of Biological Sciences

All 14,000 extant ant species descended from the same common ancestor, which lived 140–120 million years ago (Ma). While modern ants began to diversify in the Cretaceous, recent fossil evidence has demonstrated that older lineages concomitantly occupied the same ancient ecosystems. These early-diverging ant lineages, or stem ants, left no modern de...

The timing of early animal evolution remains one of the biggest conundrums in biology. Molecular data suggest Porifera diverged from the metazoan lineage some 800 Ma to 650 Ma, which contrasts with the earliest widely accepted fossils of sponges at 535 Ma. However, the lack of criteria by which to recognize the earliest animals in the fossil record...

The tempo and mode of early animal evolution remains one of the biggest conundrums in biology. Stratigraphy shows that there is a gap, not attributable to poor preservation, of at least ~100 Myr between the oldest animal fossils and the divergence times implied by molecular phylogenies. Sponges, due to their position in the metazoan tree, are a goo...

How flow moves through porous structures like sponges has long intrigued physical and biological scientists. Despite sponges having specialized cells that function as biological pumps, their porous bodies are proposed to passively take advantage of ambient currents via ‘inducedflow’. This hypothesis relies on the fact that flow external to perforat...

Herein, morphological change within a particular ammonoid lineage was investigated. This lineage existed during the terminal lower Aptian [Lower Cretaceous ~120 million years] in a shallow epicontinental sea at northeast of Mexico. This study is based in 243 samples of four ammonite species belonging to the Deshayesitidae family. These are distribu...