Happy Thought for 6 December 2024

Have a Happy Thought: 

One really cool thing about seeing footprints in sand, or mud, is coming up with a story of how those footprints were made. Was that dog running after its two humans, or was there one human with the dog, and another human walked by later? 

 

 

Scientists recently have found much older footprints and are playing the same game, trying to figure out how, or if, the various beings that made these footprints interacted. Starting with the more recent: scientists have found and dated footprints in an ancient lakebed, and have realised that sets of tracks were left by two different hominin (human ancestor or relative) species, and within at most a few days of each other! One set of footprints they belonged to a Homo erectus, and the other was left by a Paranthropus boisei (the term “australopithecine” may be more familiar to you, a more distant relative to modern humans). And these footprints were left about 1.5 million years ago – amazing they survived at all, let alone giving us enough information now to find them. 

Image: Footprints made in modern-day Kenya by Paranthropus boisei, about 1.5 million years ago. Credit: Kevin G. Hatala 

 

The other sets of footprints are even older. So old, in fact, that you have to understand plate tectonics to realise that the two sets are related. You can see where the footprints were found in the image below, the two stars, showing that one set of footprints was found in modern-day Cameroon, and the other in modern-day Brazil. This map shows what the continents would have looked like when the footprints were created, about 120 million years ago!  

Image: Showing the South Atlantic, South America and Africa approximate positions 120 million years ago. Red stars represent the locations of similar dinosaur track finds. From Jacobs et al. 

 

So while these footprints, of the same dinosaur species, were originally created only 1000 km apart, today those footprints are more than 6000 km distant from each other! And while it’s not necessarily likely, it is possible that one animal, one long-ago ostrich-like theropod, wandered along making these tracks that today are separated by the entire Atlantic Ocean. 

Image: A long ornithopod trackway in the Sousa Basin in Brazil. (Ismar de Souza Carvalho) 

 

 

Thanks to the Nature Podcast and Corey S Powell on Mastodon for bringing us these stories.