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Goniatite shells are small to medium in size, almost always less than 15 centimeters (5.9 inches) in diameter and often smaller than 5 centimeters (2.0 inches) in diameter. The shell is always planispirally coiled, unlike those of Mesozoic ammonites in which some are trochoidal and even aberrant (called heteromorphs).
The majority of ammonite species feature planispiral shells, tightly coiled in a flat plane. The most fundamental difference in spiral form is how strongly successive whorls expand and overlap their predecessors. This can be inferred by the size of the umbilicus, the sunken-in inner part of the coil, exposing older and smaller whorls.
Parapuzosia seppenradensis is the largest known species of ammonite. [1] It lived during the Lower Campanian Epoch of the Late Cretaceous period, in marine environments in what is now Westphalia, Germany.
Goniatitinae is one of six subfamilies into which the Goniatitidae is subdivided according to Miller, Furnish, and Schindewolf, 1957. The diagnostic character is the narrow bifurcated (double pronged) ventral lobe of the suture, which lies along the outer rim.
Size Reference Flatworm animal: Eucestoda: Tapeworm: length (maximum) 25 m: Eucestoda: Nematode animal: Loa loa: Loa loa: length (female) 20–70 mm: Loa loa: Arthropod animal: Cymothoa exigua: Tongue-eating louse: length (female) 8–29 mm: Cymothoa exigua: Nematode animal: Enterobius: Pinworm: length (female) 8–13 mm: Pinworm (parasite ...
Arietitidae is a family of true ammonites that make up part of the superfamily Psiloceratoidea, named after the type genus Arietites.They comprise medium-size to large or gigantic genera which in general are strongly ribbed, tuberculate in some, with keeled or grooved and keeled venters, and well differentiated ammonitic sutures.
Phricodoceratidae is a family in the Eoderoceratoidea, aberrant ammonites from the Lower Jurassic characterized by a large adult size and a marked change of shell form and ornament with growth. Shells are stoutly ribbed, early growth stage is round-whorled with spines, followed by a high-whorled late growth stage with smooth, modified ribbing.
Fontannesia is an ammonoid cephalopod genus with a small to medium size, evolute, discoidal shell that was extant during the Jurassic Period.The sides are ribbed, the venter has a single median keel, and tubercles are lacking.