Test 1

With a shell that measured 1.7 meters, the extinct mollusk Parapuzosia seppenradensis is the largest ammonite in the fossil record. Ever since fossilized remains of this large ammonite were first discovered in 1895, scientists have been perplexed by its size. After examining 154 ammonite fossils, including P. seppenradensis fossils from Texas and Parapuzosia leptophylla (a smaller ammonite species) fossils from England, paleontologists Christina Ifrim, Arturo H. González-González, and colleagues concluded that P. seppenradensis may have evolved from P. leptophylla and gradually increased in size as larger ammonites were better able to escape being preyed on by mosasaurs.

Test 2

Christina Ifrim and her team have expanded our understanding of the evolutionary history of ammonites in general, but their study has some gaps that will require additional research to fill. For instance, there’s evidence that mosasaurs preyed on ammonites, but there’s no direct evidence that they interacted specifically with P. seppenradensis.