Ludwigia Ammonite with Preserved Siphuncule

Ludwigia murchisonae

Geologic Time: Jurassic, Aalenian Stage (~173 million years ago)

Size (25.4 mm = 1 inch): 45 mm diameter

Fossil Site: Western Isles, Scotland

Fossil Code: AAF346

Price: $45.00 - sold

Description: This ammonite is known as Ludwigia murchisonae. I am not sure if the genus name is valid or not as an aquatic plant is also known as Ludwigia. Whichever was described first in the literature would have priority. Such an event happens more frequently than one might expect. It is not always easy for a researcher to determine whether someone else has already used a genus name, resulting in some very disparate organisms sharing a name until things can be sorted out. This one has intricate ribbing. Notice too the ridge along the dorsal surface of the shell. This is the siphuncule which was the means by which the ammonite would redistribute “ballast’ in order to enable it to move through the water column much like a modern-day submarine.

Ammonites Purchase

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