Baculites
extinct genus of ammonites (Ammonoidea)
Baculites is an extinct genus of heteromorph ammonite cephalopods with almost straight shells. The genus, which lived worldwide throughout most of the Late Cretaceous, and which briefly survived the K-Pg mass extinction event, was named by Lamarck in 1799.
Shell anatomy
The adult shell of Baculites is generally straight and may be either smooth or with sinuous striae or ribbing that typically slant dorso-ventrally forward. The aperture likewise slopes to the front and has a sinuous margin. The venter is narrowly rounded to acute while the dorsum is more broad. The juvenile shell, found at the apex, is coiled in one or two whorls and described as minute, about 1 centimetre (0.39 in) in diameter. Adult Baculites ranged in size from about 7 centimetres (2.8 in) (Baculites larsoni) up to 2 metres (6.6 ft) in length.
As with other ammonites, the shell consisted of a series of camerae, or chambers, that were connected to the animal by a narrow tube called a siphuncle by which gas content and thereby buoyancy could be regulated in the same manner as Nautilus does today. The chambers are separated by walls called septa. The line where each septum meets the outer shell is called the suture or suture line.
The public source identifies “Baculites” as extinct genus of ammonites (Ammonoidea). This brief keeps that definition visible, then builds a research path around Baculites, extinct and genus.
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The date and method of observation matter as much as the stated conclusion, especially where classification or consensus has changed. The source revision retrieved here is dated Sep 12, 2026. The linked authority identifier is Q1061311. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1799.
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This entry incorporates text from “Baculites” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.