Bruno Ernande, a marine evolutionary ecologist at France’s marine research institute and co-author of the study, said polarised light revealed five smaller lines for every big one. The researchers concluded the smaller lines better correlated to a year of coelacanth age — and that indicated their oldest specimen was 84 years old. a b c Peterman, David J.; Ritterbush, Kathleen A. (2022-07-04). "Resurrecting extinct cephalopods with biomimetic robots to explore hydrodynamic stability, maneuverability, and physical constraints on life habits". Scientific Reports. 12 (1): 11287. Bibcode: 2022NatSR..1211287P. doi: 10.1038/s41598-022-13006-6. ISSN 2045-2322. PMC 9253093. PMID 35787639.

A fossil can preserve an entire organism or just part of one. Bones, shells, feathers, and leaves can all become fossils. Doguzhaeva, Larisa A.; Royal H. Mapes; Herbert Summesberger; Harry Mutvei (2007). "The Preservation of Body Tissues, Shell, and Mandibles in the Ceratitid Ammonoid Austrotrachyceras (Late Triassic), Austria". In N. H. Landman; etal. (eds.). Cephalopods Present and Past: New Insights and Fresh Perspectives. Dordrecht: Springer. pp. 221–238. doi: 10.1007/978-1-4020-6806-5_11. ISBN 978-1-4020-6806-5.

A fossil (from Classical Latin fossilis, lit. 'obtained by digging') [1] is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the fossil record.

While nearly all nautiloids show gently curving sutures, the ammonoid suture line (the intersection of the septum with the outer shell) is variably folded, forming saddles ("peaks" that point towards the aperture) and lobes ("valleys" which point away from the aperture). The suture line has four main regions. Gittenberger, E. (1991). "What about non-adaptive radiation?". Biological Journal of the Linnean Society. 43 (4): 263–272. doi: 10.1111/j.1095-8312.1991.tb00598.x. Preserved remains become fossils if they reach an age of about 10,000 years. Fossils can come from the Archaeaean Eon (which began almost four billion years ago) all the way up to the Holocene Epoch (which continues today). The fossilized teeth of wooly mammoths are some of our most "recent" fossils. Some of the oldest fossils are those of ancient algae that lived in the ocean more than three billion years ago. Before the body disappears completely, it is buried by sediment - usually mud, sand or silt. Often at this point only the bones and teeth remain. Acanthisittidae (New Zealand "wrens") – 2living species, a few more recently extinct. Distinct lineage of Passeriformes.There are many processes that lead to fossilization, including permineralization, casts and molds, authigenic mineralization, replacement and recrystallization, adpression, carbonization, and bioimmuration.

Living Fossil" redirects here. For the story by L. Sprague de Camp, see Living Fossil (short story). Spicomellus is the oldest known ankylosaur and the first found in Africa. It’s also a creature with no known analogue, living or dead. “If you feel your own ribs, there’s muscles over the top of them that allow your arms to move,” says Susannah Maidment, the paleontologist at London’s Natural History Museum who led the research on Spicomellus. “What were they doing with their muscles when their ribs clearly had spikes above the skin?” Rowe, Alison J.; Landman, Neil H.; Cochran, J. Kirk; Witts, James D.; Garb, Matthew P. (26 March 2020). "Late Cretaceous Methane Seeps as Habitats for Newly Hatched Ammonites". PALAIOS. 35 (3): 151–163. Bibcode: 2020Palai..35..151R. doi: 10.2110/palo.2019.105. S2CID 214718487.

How big were ammonites?

Some paleontologists believe that living fossils with large distributions (such as Triops cancriformis) are not real living fossils. In the case of Triops cancriformis (living from the Triassic until now), the Triassic specimens lost most of their appendages (mostly only carapaces remain), and they have not been thoroughly examined since 1938.

The term “living fossil” is an imperfect concept, which has caused much consternation among paleontologists and biologists as they have sifted through the fossil record over time. It is meant to describe an organism that has remained relatively unchanged over millions of years, or one that has no, or very few, close surviving relatives. The concept is an informal window into the past, a way for us to consider species as they may have been millions of years ago by observing their modern descendents. a b Gu, H.; Kirsch, M.; Zinßmeister, C.; Söhner, S.; Meier, K.J.S.; Liu, T.; Gottschling, M. (2013). "Waking the dead: Morphological and molecular characterization of extant † Posoniella tricarinelloides (Thoracosphaeraceae, Dinophyceae)". Protist. 164 (5): 583–597. doi: 10.1016/j.protis.2013.06.001. PMID 23850812. The Australian lungfish ( Neoceratodus fosteri), also known as the Queensland lungfish, is an example of an organism that meets this criterion. Fossils identical to modern specimens have been dated at over 100 million years old. Modern Queensland lungfish have existed as a species for almost 30 million years. The contemporary nurse shark has existed for more than 112 million years, making this species one of the oldest, if not actually the oldest extant vertebrate species. Pelicans ( Pelecanus) – form has been virtually unchanged since the Eocene, and is noted to have been even more conserved across the Cenozoic than that of crocodiles. [48] A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossils commonly are of species-poor lineages, but they need not be. While the body plan of a living fossil remains superficially similar, it is never the same species as the remote relatives it resembles, because genetic drift would inevitably change its chromosomal structure.When ammonites are found in clays, their original mother-of-pearl coating is often preserved. This type of preservation is found in ammonites such as Hoplites from the Cretaceous Gault clay of Folkestone in Kent, England.