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Life and Death in the Devonian - Cleveland Shale

Cleveland Shale, Late Devonian (Famenian) where it would become Ohio, USA.

In shallow waters, a large and old Titanichthys clarki appears giving birth to a young. This giant filter feeder was one of the largest placoderm fishes, reaching around 4,15 m*.

The female's weakened movement and the smell of blood attract unwanted attention: a trio of "small" (about 1,5 m) Cladoselache sp., shark-like holocephalans (relatives of modern chimaeras), swims towards the young. The size of the newborn would possibly already discourage these predators of small prey, but in any case they will be startled by a Gorgonichthys clarki that approaches from the right. This "saber-toothed" placoderm, also of a large size (perhaps also around 4 m), would prefer smaller prey without armor, being more interested in those "sharks" than in other placoderms.

From a distance, a greater danger also noted the mother and its baby: a Dunkleosteus terrelli, one of the candidates for largest placoderm (with 3,4-4 m in length*). The dimensions and "armor" of Titanichthys shouldn't make it safe against this large predator with a crushing bite.

Another species of Titanichthys, the smaller T. agassizi, is seen feeding in a small group far away. Conodonts, ammonoids and some corals (rugose and tabulate) also appear. The latter were very present throughout the Devonian, but rare in this scene from the end of the Period, as microbial organisms, represented here by stromatolites and a a dark mud of microbial mats, were taking the place of animals in the formation of reefs, due the anoxic water of the bottom.

New artwork for Tales from the Phanerozoic, a project by João Macêdo. Check it out: https://sites.google.com/view/talesfromthephanerozoic/

*Update 26/11/23: among other small adjustments, the placoderms had their body proportions reworked. Engelman (2023) proposed a new method for calculating the length of Dunkleosteus (using the orbit-opercular length), resulting in smaller estimates than previous ones and a more robust, stocky appearance for these fishes. The new method predicts the length of other fish, including placoderms with preserved body impressions, with considerable precision, so it may be our best attempt to estimate the size of these animals yet.

Mother Titanichthys clarki

Mother Titanichthys clarki

Baby Titanichthys clarki

Baby Titanichthys clarki

Dunkleosteus

Dunkleosteus

Gorgonichthys

Gorgonichthys

Cladoselache

Cladoselache

Titanichthys agassizi

Titanichthys agassizi