Urethra isn’t a hole though, it’s just a depression. Mouth and anus are the same hole.

Fun fact: what ever you eat is wrapped around by your body, but it’s not in the body.

Humans are topologically a seven? hole donut.

Sounds like wolf spiders. They are actually good mammas and they haul their 'lings on their backs until they are old enough to disperse.

And since all land vertebrates are descendents of fish, and you can’t evolve out of a clade, whales actually are fish.

Playing FTL taught me that when you need to reroute power, life support is the first to go.

Keeping weapons hot, engines full and shields up make you dish out or avoid damage. The crew can hold their breath.

Oxygen levels wouldn’t be a factor. The “need high oxygen levels for large size” only applies to invertebrates with very simple breathing systems.

If trex had similar type of lungs as modern birds, they would do just fine. Bird lungs are super efficient (much better than mammals’ puny blind sack lungs) that enable them to fly at high altitudes.