Sarti, Carlo (1999). "Whorl Width in the Body Chamber of Ammonites as a Sign of Dimorphism". Advancing Research on Living and Fossil Cephalopods. pp.315–332. doi: 10.1007/978-1-4615-4837-9_23. ISBN 978-1-4613-7193-9. IUCN Red List Of Threatened Species: Nasikabatrachus Sahyadrensis". IUCN Red List Of Threatened Species. Ammonites (subclass Ammonoidea) can be distinguished by their septa, the dividing walls that separate the chambers in the phragmocone, by the nature of their sutures where the septa join the outer shell wall, and in general by their siphuncles. Heteromorphs [ edit ] Baculites ammonite from the Late Cretaceous of Wyoming, US: The original aragonite of the outer conch and inner septa has dissolved away, leaving this articulated internal mold. Heteromorph ammonite Didymoceras stevensoni

a b Montresor, M.; Janofske, D.; Willems, H. (1997). "The cyst-theca relationship in Calciodinellum operosum emend. (Peridiniales, Dinophyceae) and a new approach for the study of calcareous cysts". Journal of Phycology. 33 (1): 122–131. doi: 10.1111/j.0022-3646.1997.00122.x. S2CID 84169394. Crinoids were thought to be extinct until 2021. NOAA Ocean Exploration and Research How do living fossils form? Cavin, Lionel; Guinot, Guillaume (13 August 2014). Coelacanths as "almost living fossils". Muséum d'Histoire Naturelle (Report). Perspective Article. Genève, Switzerland: Département de Géologie et Paléontologie. doi: 10.3389/fevo.2014.00049. They show little morphological divergence, whether from early members of the lineage, or among extant species.

Where did ammonites live?

Soft parts, preserved under special circumstances insedimentary deposits known as Lagerstätten (singular Lagerstätte), are known for a few trilobite species. From these, geologists know that trilobites had a pair of jointed antennae protruding forwards from beneath the cephalon and rows of jointed limbs on each side of the body.

Chambers, T.C.; Drinnan, A.N.; McLoughlin, S. (1998). "Some morphological features of Wollemi Pine (Wollemia nobilis: Araucariaceae) and their comparison to Cretaceous plant fossils". International Journal of Plant Sciences. 159: 160–171. doi: 10.1086/297534. S2CID 84425685. In November a Brazilian research team unveiled a remarkable toothless dinosaur in the journal Scientific Reports. The fossil creature, called Berthasaura leopoldinae, is the most complete fossil of its kind and age ever found in Brazil. It is named for two influential Brazilian women: Bertha Maria Júlia Lutz, a zoologist and pioneering women’s rights advocate, and Brazil’s first empress, Maria Leopoldina, who played a pivotal role in securing the country’s independence.Any one of the above three definitions, but also with a relict distribution in refuges. [ citation needed]