It uses a combination of D3, SVG, and Canvas elements to create the different visualizations. The main visualization is a timeline + map showing the prehistoric creatures in chronological order by time period. It maps them to their location of origin and also displays fossils at their discovery sites. An overlay of pangea can also be projected onto the map.
Code available on Github here. Created using all free resources and open source code:
The fossil data is from the Paleo Database at Paleobiodb.org
The timeline + map section were originally forked from the open source Svelte visualization project and influenced by the Foreign Interference Attribution Tracker and it's developer Matthias Stahl (higsch | data & design)
Additional images and information from Smithsonian Dinosaur atlas, Wikipedia, and other free sources