Eulipotyphla

HBDchick alerted her twitter followers to the venomous members of the mammalian Insectivora - the Solenodonts. These critters survive in Cuba and Hispaniola. They had relatives in other Caribbean islands, now defunct.

I'd lost track of these little guys since my schooldays but, since then, they've been deemed paraphyletic. That is, "Insectivora" is a description - describing "fuzzy things that eat bugs"; not a classification. What is a classification is the Eulipotyphla, containing solenodonts and shrews. They split 70 mya.

This split happened in what used to be Laurasia, scattered between (eastern) North America, Greenland, and Europe.

That's before Chicxulub. This was the Dark Age in the synapsid-to-Palaeogene timeline, but we're getting a lot better at it. There's a whole clade of "Laurasiatheria" diversifying 91-76 mya, which gave rise to Eulipotyphla in the first place... alongside ungulates, whales, bats, (most) carnivores. Probably because they were all different island-continents, then still close enough to be mutually raftable. Our rodent-primate group developed in Europe. Our males all share the trait that we have a scrotum, so we're likely a sister or, rather, brother to this lot.

There's talk that the ancestor to all mammals might have been venomous; the surviving monotremes are (famously) venomous.

I liked this idea but then I made the mistake of doing some research. Eulipotyphla venom is convergent. That means shrew venom isn't solenodont venom; they evolved differently (paraphylesis again). Very probably the basal Eulipotyphlon wasn't venomous or, why un-evolve it and re-evolve it.

To find if the basal placental was venomous, we need to look elsewhere. The Eulipotyphla are anti-evidence.

CENTAUR 9/3/2021: Heart's in the right place. Dates, on the other hand... 60 Mya? I mean, I know that other (P/E 55 Mya) boundary was a Thing, but . . .