Mosasaurs most likely became extinct during the K/T mass extinction, together with the remaining sauropterygians and many other animals.
The distinctive limy tests (internal skeletons of calcium carbonate) of crinoids make the thousands of extinct species (together with extinct echinoderms of similar form) important Paleozoic index fossils.
"However, we can speculate that if the trajectory of dinosaurs continued as it was at that time, dinosaurs would eventually have become impoverished in terms of species numbers -- and may have gone extinct all together".
Within Mecoptera, Mesopsychidae Tillyard, 1917, are a small extinct family, and together with three other families, Aneuretopsychidae [ 7], Pseudopolycentropodidae [ 8], and Nedubroviidae [ 9], form a major clade of basal Mecoptera, the Aneuretopsychina [ 10], which have elongate, siphonate proboscides, feeding on pollination drops of gymnosperms [ 3, 11, 12].
And why did they all go extinct, and so close together in time?
The way they tell it in their report in Science Advances: The three plates lying beneath the now-extinct Panthalassa Ocean came together in a Y-shaped configuration and began to slide against each other in a pinwheel motion, leaving a triangular gap in the center.
The fossil and living tapirs, together with similar extinct forms such as the lophiodonts, constitute a small, fairly uniform group.
MAGE would allow scientists to start with an intact genome of a living Asian elephant and change it wholesale into one that is comparable to an extinct mammoth, using information pieced together from frozen fragments of mammoths.
The various degrees of difference in the languages from the same stock, would have to be expressed by groups subordinate to groups; but the proper or even only possible arrangement would still be genealogical; and this would be strictly natural, as it would connect together all languages, extinct and modern, by the closest affinities, and would give the filiation and origin of each tongue.
