Really simplified animal kingdom hierarchy:
. └── Animal | ├── Invertebrate | | │ └── Mollusc │ └── Vertebrate | ├── Fish | ├── Mammal | | │ └── Primate | | │ ├── Homo | ├── Reptile
As support code for my post on lansalo.com
See here: https://lansalo.com/2017/10/22/scala-variance-explained/