Search results
Results from the WOW.Com Content Network
The topology of the septa, especially around the rim, results in the various suture patterns found. [5] The septal curvature in nautiloids and ammonoids also differ in that the septa curves towards the opening in nautiloids, and away from the opening in ammоnoids. [6] Regions of the suture line and variants in suture patterns Ammonite clean cut
The sutures of nautiloids are by comparison somewhat simpler, being either straight or slightly curved, whereas later ammonoids showed suture patterns of increasing complexity. One explanation for this increasing extravagancy in suture pattern is that it leads to a higher strength of the shell.
This ammonite has a ceratitic suture pattern on its shell (smooth lobes and frilly saddles). Evolution of the frilly saddles is thought to be due to increased pressure on the shell, at greater depth. The frilly pattern would increase the strength of the shell and allow Ceratites to dive deeper, possibly in search of food. [citation needed]
Suture morphology in the Prolecanitida changed dramatically over time, from very simple sutures in the earliest genera to much more complex-sutured genera in the late Paleozoic. The increase in suture complexity over the 108 m.y. duration resulted from the iterative of addition of umbilical lobes, increasing serration of lobes, and the ...
Sutures are generally ammonitic, characterized by complex saddle and lobe patterns. However, in some derived forms, the suture pattern becomes simplified, appearing ceratitic or even goniatitic. The Ammonitina are derived from the Phylloceratina, another ammonitid suborder which has its origin in the Ceratitida of the Triassic .
Genera of the Uddenitinae have narrow discoidal shells with narrow flat or sometimes grooved venters. Sutures are goniatitic to ceratitic with rounded saddles and slightly pointed to digitate lobes which form a declining series going toward the umbilicus. The ventral lobe is commonly long and narrow, and trifurcated with sharp, simple prongs.
Daraelitids are probably ancestral to Ceratitida, the dominant order of Triassic ammonoids. A third proposed family, the Mississippian-age Prodromitidae, is occasionally also placed within the order Prolecanitida. [1] The affinities or monophyly of this family are uncertain due to drastic changes in their suture patterns through ontogeny.
Suture pattern of Scaphites Reconstructions of the body within the shell can be made to portray Scaphites as either a benthic (bottom-dwelling) or planktonic animal, depending on where the center of gravity is located.