The Magic School Bus In the Time of the Dinosaurs to after he fought the T-Rex; which made Arnold leave the sneaker footprint from his shoe due to his giant size). When Ms. Frizzle says she wonders what giant creature left that footprint, this is what Carlos says in response. Carlos says "I'd say it was a 'Sneakersaurus'!". Ms. Frizzle is missing some photographs from her photo album of her last trip to the age of dinosaurs. As usual, the user has to find replacements. There are seven different places, including "Triassic Arizona", "Triassic Argentina", "Jurassic Colorado", "Jurassic Tethys Sea", "Jurassic Tanzania", "Cretaceous Alberta", and "Cretaceous Mongolia". Here in the
Mesangiospermae are fossil mesangiosperms from the Hauterivian stage of the Cretaceous period. Molecular clock comparisons of DNA sequences indicate that the mesangiosperms originated between 140 and 150 Mya (million years ago) near the beginning of the Cretaceous period. This was about 25 Ma (million years) after the origin of the angiosperms in the mid-Jurassic. By 135Mya, the mesangiosperms had radiated into 5 groups: Chloranthales, Magnoliids, Monocots, Ceratophyllales, and Eudicots. The radiation into 5 groups probably occurred in about 4 million years. Because the interval of this radiation (about 4 million years) is short in proportion to its age (about 145 million