Tyrmeidae

Tyrmeidae is a poorly understood and potentially invalid taxonomic name that has appeared in the scientific literature, primarily relating to extinct arthropods. It is often associated with the classification of fossil millipedes (Diplopoda) or myriapod-like arthropods from the Paleozoic era, specifically the Devonian and Carboniferous periods.

The exact validity and phylogenetic placement of Tyrmeidae is uncertain due to the fragmentary nature of the fossil record and inconsistencies in its usage across different publications. Some researchers consider it a synonym of other more well-established millipede families or orders, while others suggest it might represent a distinct, albeit poorly defined, lineage.

The defining characteristics of purported Tyrmeidae members are typically based on features like the number of segments, the presence or absence of keels or other ornamentation on the tergites (dorsal plates), and the morphology of the legs. However, these features can be difficult to interpret from incomplete fossils, leading to ongoing debate and revisions in classification.

Due to the taxonomic ambiguity surrounding Tyrmeidae, it is often excluded from modern cladistic analyses of millipede evolution. Further investigation and more complete fossil discoveries are needed to clarify the validity and relationships of this group. Its historical use, however, underscores the challenges inherent in reconstructing the evolutionary history of early terrestrial arthropods.