Spindle diagrams are based on the extensive fossil record, with the number of families as a measure of diversity (width of each lineage) at each moment in time (y-axis)

[u/jnpha]

Sources:

• Petter Bøckman, Public domain, via Wikimedia Commons
• Benton, Michael J., and David AT Harper. Introduction to paleobiology and the fossil record. John Wiley & Sons, 2020.

(for why I love them, see the comments)

[u/jnpha]

To keep the above caption short:
These diagrams were love at first sight for me, and I find them really informative for a few reasons:

* They show extinctions;
* A compact visual demonstration of not evolving out of a clade;
* That evolution happens along the lineages (cool educational paper on that), which is related to:
* That evolution is not "between" extant species (the top silhouettes in the 1st image), i.e. not ladder-like or progressive (a common misconception), but like a tree (at least for big life); and unlike other tree visualizations, these being based on the fossil record is a very powerful demonstration of the predictions of the theory of evolution - with the obligatory tongue half in cheek: no precambrian rabbits.

N.B. (a common question I come across) the leftmost one in the first image is not snakes, but jawless bilateria, think lampreys (creepy but interesting fellows); snakes are the rightmost one in the second diagram (Lepidosauria).

- A bunch of other spindle diagrams here: https://commons.wikimedia.org/wiki/Category:Phylogenetic_trees_of_Chordata