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15-piece box; Long Baculites, with 1 piece measuring 16″ long


Baculites (“walking stick rock”) is an extinct genus of cephalopods with a nearly straight shell, included in the heteromorph ammonites. 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 broader. The juvenile shell, found at the apex, is coiled in one or two whorls and described as minute, about 1 centimeter (0.39 in) in diameter. Adult Baculites ranged in size from about 7 centimeters (2.8 in) (Baculites larsoni) up to 2 meters (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. Like other true ammonites, Baculites have intricate suture patterns on their shells that can be used to identify different species.

One notable feature about Baculites is that the males may have been a third to a half the size of the females and may have had much lighter ribbing on the surface of the shell.

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