# No evidence for niche competition in the extinction of the South American saber-tooth species

## TL;DR

This study finds that climate, not competition with North American species, likely caused the extinction of South American saber-tooth cats.

## Contribution

The paper provides new evidence that climate niche differences, not competition, explain the extinction of Thylacosmilus atrox.

## Key findings

- Thylacosmilus atrox had a narrower climatic niche compared to Smilodon species.
- Low niche overlap between Thylacosmilus atrox and Smilodon populator suggests no competitive interaction.
- Climatic niche and low environmental tolerance likely caused the extinction of Thylacosmilus atrox.

## Abstract

The end of South American isolation during the Great American Biotic Interchange (GABI) promoted the contact between South and North American saber-tooth forms that evolved in isolation. This contact may have driven saber-tooth species to a competitive interaction, resulting in the extinction of the South American saber-tooth form. Here, we used paleoclimatic data to compare the climatic niche of the saber-tooth forms Thylacosmilus atrox (from South America), Smilodon fatalis, and Smilodon populator (both originally from North America). We evaluated niche width, overlap, and similarity to infer potential geographic distribution overlap and competition between these North and South American predators. To do so, we obtained the climatic variables from sites where occurrence fossil records were available. Our results suggest that T. atrox had a narrower climatic niche compared to Smilodon species. Although we found a significant climatic niche overlap and similarity between S. fatalis and T. atrox, it seems unlikely that both species have co-occurred. Low niche overlap and similarity between T. atrox and S. populator dismiss competitive interaction between them. Moreover, climatic niche and low tolerance for environmental changes may have been the cause of the South American saber-tooth extinction.