Original paper
Rare Arachnostega traces in brachiopod and gastropod molds from the Silurian of Gotland (Sweden) and Saaremaa (Estonia): was tropical climate unfavorable for the trace makers?
Vinn, Olev; Wilson, Mark A.; Isakar, Mare; Toom, Ursula
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 313 Heft 2 (2025), p. 153 - 159
19 references
published: Jan 30, 2025
published online: Dec 9, 2024
manuscript accepted: Nov 20, 2024
manuscript received: Nov 8, 2024
ArtNo. ESP155031302005, Price: 29.00 €
Abstract
Arachnostega gastrochaenae burrows occur in internal molds of the brachiopod Estonirhynchia estonica in the Wenlock of Saaremaa, Estonia, and in gastropod steinkerns in the Wenlock of Gotland, Sweden. The trace-making worms either entered the shell through the slit between the closed brachiopod valves as juveniles, or they used the brachiopod foramen to enter the shell interior. The Arachnostega traces in closed brachiopod shells are hidden until shell fragments are removed, exposing the internal mold. Because they are hidden in complete, articulated shells, Arachnostega may be more common in the Silurian of Baltica than currently recognized, though markedly less common than in the Ordovician. The trace makers responsible for burrows in brachiopods and gastropods presumably persisted from the Ordovician to the Silurian. The rarity of Arachnostega burrows in the Silurian of Baltica as compared to that of early Late Ordovician supports the view that, at least during the early Paleozoic, Arachnostega trace makers preferred colder climates.
Keywords
Steinkerns • burrows • Arachnostega • gastropods • brachiopods • Silurian • Baltica