Oops, We Did It Again -- Energy Sector This Year -- You Never Expect To See This -- "Worst Results Ever" -- February 17, 2023

Link here.

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The Book Page
The Rise and Reign of the Mammals
Steve Brusatte
c. 2022

In round numbers:

• amphibians appear on land, 365 million years ago
• the "link" from amphibian to reptile/mammal ancestor appears: 300 million years ago
• mammal/reptile split --> direct mammalian ancestor (cynodont): 260 million years ago
• dinosaurs appear: 250 million years ago
• mammals flourish; non-dinosaur reptiles persist (birds, crocodile and their ancestors)

Amphibians --> reptile/mammal ancestor

• skull difference
• one group develops two large skull openings behind each of their eyes -->disapsids --> reptiles
• the other group: the two large skull openings fuse into one --> synapsids --> mammals
• for test-taking, how does one remember which is which?
• these large openings -- windows -- fenestrae -- that's where muscles attach
• the stronger the muscles, the more windows needed
• which have stronger jaw muscles: crocodiles or humans?
• so, crocodiles are diapsids; mammals are synapsids
• note: the synapsides in humans have anatomically closed but one can feel "functional" "windows" - the synapsid -- when opening and closing jaws

This book is c. 2022 but it's already somewhat out of date, or perhaps in period of transition

• the ancestor -- amphibian -->reptile/mammal ancestor -- has most recently been "called" a pelycosaur
• but now, pelycosaur is already falling out of favor
• pelycosaur is still used informally, as in this book, but purists in formal settings use a new term
  
• now, the preferred term: Eupelycosauria (Eu = true; pelycosaur)
• the term Eupelycosauria includes most pelycosaurs, but also Therapsida and Mammalia