Tag: trace fossil

Eons Roundup 14

It’s been a while, but let’s catch up with some more work I’ve done for PBS Eons:

An illustration of both a fossil example and the reconstructed internal structure of the enigmatic Paleodictyon, a hexagonal network of tunnels in seafloor sediment created by an unknown organism.
Paleodictyon nodosum

The enigmatic Paleodictyon, from “Something Has Been Making This Mark For 500 Million Years”

An illustration of Loxolophus, an extinct mammal related to early ungulates. It somewhat resembles a modern coatimundi, with a slender snout, long legs with plantigrade feet and claw-like hooves, and a long bushy tail. It's reconstructed with a mottled and striped camouflage pattern of brown and cream fur.
Loxolophus hyattianus
An illustration of Arctocyon, an extinct mammal related to early ungulates. It has a dog-like head with large canine teeth, a stocky bear-like body with plantigrade legs and claw-like hooves, and a long tail. It's reconstructed with an orange-brown pelt with white stripes along its limbs.
Arctocyon primaevus
An illustration of Eoconodon, an extinct mammal related to early ungulates. It has a somewhat deer-like head, a rather cat-like body shape, claw-like hooves on its toes, and a long tail. It's reconstructed with a coat of brown fur spotted with white along its back and sides.
Eoconodon coryphaeus

The archaic ungulates Loxolophus, Arctocyon, and Eoconodon, from “How a Mass Extinction Changed Our Brains”

An illustration of Aturia, an extinct relative of modern nautiluses. It's reconstructed with an orange-brown shell patterned with zigzagging darker stripes.
Aturia sp.

And the nautilid Aturia, from “When Nautiloids Met Their Match”

Unsolved Paleo Mysteries Month #02 – The Paleodictyon Problem

Paleodictyon is the name for a net-like pattern found in the marine fossil record, starting in the Late Precambrian/Early Cambrian (~541 mya). Formed from thin tubes in seafloor sediment, each element of the mesh is around 1-3cm in diameter (0.4-1.1″), with entire networks covering areas of up to a square meter (10.7ft²). Some forms also have vertical tubes connecting the mesh to the surface.

And nobody knows what it is.

These patterns have even been found on the modern day seafloor at mid-ocean ridges. Samples have been taken, DNA tests have been performed… and nothing conclusive has yet been found.

Whatever makes these patterns is alive today, but we still don’t know what it is!

There are two main hypotheses about the mysterious identity of the mesh-maker. It might be some sort of small worm-like animal excavating burrows, engineering water flow through the tubes to collect food. Or the whole mesh might be the body imprint of a single creature – either a sponge or a giant foraminiferan.

Hopefully one day somebody will finally catch the Paleodictyon culprit in the act.