Palaeopalaemon newberryi

Overview

Palaeopalaemon is a Late Devonian crustacean with a cylindrical carapace, long rostrum, and segmented abdomen. Appendages near the mouth, walking legs, and the tail have different constructions. It evokes a lobster while offering different features in each region.^[1]

Key facts

Not all its legs bear the same kind of claw. Large rake-like maxillipeds near the mouth, a scissor-like first walking leg, and smaller or more slender legs behind are distinguished. It is intriguing to consider appendage position and shape separately.^[1]

Time and place

It is known from research on Late Devonian specimens assigned to the species. The Devonian as a whole was roughly 420–360 million years ago. Researchers gathered clues to the head and thorax, abdomen, and tail from several specimens.^[1][2]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

A long rostrum projects in front of the cylindrical carapace, and long antennae are also described. The abdomen has six segments, the first short. Behind are a lance-shaped telson and tail appendages with inner and outer parts of different widths.^[1]

One fossil of Palaeopalaemon newberryi had a carapace covering the head and thorax that measured 2.2cm, and an estimated body length of about 5cm excluding the terminal telson. Although a large lobster may come to mind, this specimen’s body was closer to a finger in length.^[3]

Habitat and reproduction

Where were the different anterior appendages positioned? A large third maxilliped, the first walking leg, and smaller legs behind it are distinguished in sequence. Considering names and positions together reveals different constructions within the same body.^[1]

Fossil discovery

Morphological research compared carapaces, appendages, abdomens, and tails in several specimens assigned to the species. The author’s composite illustration organized these different sources into one body construction. Partial fossils thus lead to questions about the whole.^[1]

References

1. Study — Morphology and palaeoecology of Palaeopalaemon
2. International Commission on Stratigraphy (2024) — Geological time chart
3. Brooks (1962) — Paleozoic crustaceans of North America
4. Rathbun (1917) — Description of a Cretaceous crab from South Dakota
5. Bishop et al. (1998) — Comparing the eyes and claws of dakoticancrids

Research questions

Were the inner and outer appendages forming the tail fan the same width? The description distinguishes broad inner and narrow outer structures. Even a tail that looks like one unit can be read in several parts.^[1]

Observation

Move your gaze from the large appendages near the mouth to the first walking leg and the legs behind it. Then follow the six abdominal segments and tail fan to see clear differences in construction between front and rear.^[1]