11. Some time after laying her eggs, another gravid " Dimetrodon " tries to take over her nest. 12. These trackways include tracks from numerous extinct animals such as " Dimetrodon " and " Edaphosaurus ". 13. Within a minute the volcanic gases in the inflated dimetrodon explode, killing the cannibals who had swarmed over the balloon. 14. Whilst exploring the island, they find more Brontosaurus and later, a dimetrodon ( a sail-backed synapsid ). 15. Beginning in the late 1920s, paleontologist Alfred Romer restudied many " Dimetrodon " specimens and named several new species. 16. Larger bodied specimens of " Dimetrodon " have larger sails relative to their size, an example of positive allometry. 17. Some specimens of " Dimetrodon " preserve deformed areas of the neural spines that appear to be healed-over fractures. 18. They construct a raft from the stems of giant mushrooms to cross it but, not before narrowly escaping a family of dimetrodons . 19. Unlike " Albertosaurus ", " Dimetrodon " teeth lacked adaptations that would stop cracks from forming at their serrations. 20. Like the closely related " Dimetrodon ", " Sphenacodon " was a carnivorous member of the Eupelycosauria family Sphenacodontidae.
