Mercaticeras
Mercaticeras is an extinct genus of ammonites belonging to the family Hildoceratidae. Etymology. The genus name "Mercaticeras" derives from Michele Mercati (a Tuscan physician who lived in the 16th century, superintendent of the Vatican Botanical Gardens) and "ceras" = horn, therefore the genus name means "horn of Mercati". Description. "Mercaticeras" shows a subquadratic section, sometimes wider than high. The shell is averagely evolute, with a spiral that grows more rapidly in the internal whirls. It is adorned by sturdy, clavate, simple ribs. The suture is simple. Fossil record. These ammonites lived in the Jurassic, Middle Toarcian age, Bifrons Zone  to lower Variabilis/Gradatus Zone (age range: 182.0 to 175.6 million years ago). Fossils of this genus can be found in Albania, Algeria, Austria, Bulgaria, Canada, France, Germany, Greece, Herzegovina, Hungary, Italy, Morocco, Portugal, Spain, Switzerland, Tunisia, Turkey. Species. Species within this genus include: Classification. The suprageneric classification has been discussed in the literature. Researchers of the Toarcian Mediterranean domain agree that "Mercaticeras" belongs to the subfamily Mercaticeratinae Guex, 1974 (Hildoceratidae) with genera "Praemercaticeras" Venturi, 1981, "Pseudomercaticeras" Merla, 1932, "Merlaites" Gabilly, 1974, "Crassiceras" Merla, 1932, and "Pseudocrassiceras" Rulleau et Jattiot, 2019.