Trigonotarbids: spider-like animals

The trigonotarbids are an extinct order within the spider-like animals (Arachnida) and they are related to the modern spiders without being real spiders. They existed from the late Silurian till in the Early Permian. Maiocercus celticus from the Late Carboniferous of Ibbenbüren also belongs to this group. They are well preserved in the Rhynie chert, as becomes clear from the photos. Sometimes even the booklungs have been preserved.
The differences with real spiders are as follows:
- trigonotarbids didn't have spinnerets
- trigonotarbids were in the possession of a segmented exoskeleton around the abdomen
- trigonotarbids had median eyes and lateral eyes placed on separate tubercles (and not on one tubercle like the real spiders).
The body is composed of a head region (prosoma) and an abdomen (opisthosoma).
Remains of trigonotarbids are easily recognized by the scale-like structure of the plates. The presence of setae (flexible hairs) in the mouth region is also characteristic for this group.
Five species have been described in the past but probably only two of them are valid, of which Palaeocharinus rhyniensis is the most common one.
Recently a third species has been described.
Go for an extensive description of this genus to the website of the University of Aberdeen.

Reconstructions of Palaeocharinus rhyniensis by Dr. Jason Dunlop, Berlin
Click here to see the impressive 3-D reconstruction by Dr. Dunlop.


Transverse section and abdomen

Head with mouth parts, and a walking leg

Distal part of a leg with a claw

Part of the abdomen with ornamentation

Part of a leg with hairs

Scale-like surface of the carapace

Mouth region with fang