Ataxioceras discobolum
Ataxioceras discobolum is a species of ammonite from the Late Jurassic, specifically the Unter‑Kimmeridgian (approximately 155–153 Ma). It is found in the marine sediments of the Kulmbach–Kirchleus area, in the Franconian Alb (Bavaria, Germany), a classic locality for Kimmeridgian studies in Europe.
The shell of this ammonite is moderately evolute and displays dense, sharply defined ribbing. The primary ribs (around 32–36 per whorl, typical for the genus) originate at the umbilical shoulder and bifurcate midway across the flank. Tertiary and even quaternary bifurcations are frequently observed, a distinctive trait of Ataxioceras. The umbilicus occupies about 40% of the shell diameter, consistent with the characteristic morphology of the genus.
Scientific classification:
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Perisphinctoidea
Family: Ataxioceratidae
Genus: Ataxioceras
Species: Ataxioceras discobolum
Era: Mesozoic
Period: Late Jurassic (Unter‑Kimmeridgian, ~155–153 Ma)
Origin: Kulmbach–Kirchleus, Franconian Alb, Bavaria, Germany
Specimen diameter: 70 mm
Fossils of A. discobolum from Kulmbach–Kirchleus occur in sediments belonging to the Hypselocyclum–Lothari Zone of the Unter‑Kimmeridgian, representing a shallow epicontinental marine environment. They serve as index fossils for identifying that stratigraphic interval. The presence of this ammonite confirms the correlation of Bavarian strata with coeval sequences in southern Germany and other parts of Europe.
Ataxioceras discobolum
Ataxioceras discobolum is a species of ammonite from the Late Jurassic, specifically the Unter‑Kimmeridgian (approximately 155–153 Ma). It is found in the marine sediments of the Kulmbach–Kirchleus area, in the Franconian Alb (Bavaria, Germany), a classic locality for Kimmeridgian studies in Europe.
The shell of this ammonite is moderately evolute and displays dense, sharply defined ribbing. The primary ribs (around 32–36 per whorl, typical for the genus) originate at the umbilical shoulder and bifurcate midway across the flank. Tertiary and even quaternary bifurcations are frequently observed, a distinctive trait of Ataxioceras. The umbilicus occupies about 40% of the shell diameter, consistent with the characteristic morphology of the genus.
Scientific classification:
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Order: Ammonitida
Superfamily: Perisphinctoidea
Family: Ataxioceratidae
Genus: Ataxioceras
Species: Ataxioceras discobolum
Era: Mesozoic
Period: Late Jurassic (Unter‑Kimmeridgian, ~155–153 Ma)
Origin: Kulmbach–Kirchleus, Franconian Alb, Bavaria, Germany
Specimen diameter: 70 mm
Fossils of A. discobolum from Kulmbach–Kirchleus occur in sediments belonging to the Hypselocyclum–Lothari Zone of the Unter‑Kimmeridgian, representing a shallow epicontinental marine environment. They serve as index fossils for identifying that stratigraphic interval. The presence of this ammonite confirms the correlation of Bavarian strata with coeval sequences in southern Germany and other parts of Europe.