Great appendages are large claw

Claw

A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...

-like appendage

Appendage

In invertebrate biology, an appendage is an external body part, or natural prolongation, that protrudes from an organism's body . It is a general term that covers any of the homologous body parts that may extend from a body segment...

s which attach to the heads of the "great appendage arthropods", a group whose monophyly

Monophyly

In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

 is debated, but which includes the anomalocaridids. The great appendages are used in food manipulation; Anomalocaris

Anomalocaris

Anomalocaris is an extinct genus of anomalocaridid, which are, in turn, thought to be closely related to the arthropods. The first fossils of Anomalocaris were discovered in the Ogygopsis Shale by Joseph Frederick Whiteaves, with more examples found by Charles Doolittle Walcott in the famed...

used them to manipulate prey such as trilobite

Trilobite

Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...

s, while Laggania

Laggania

Laggania cambria was a species of Anomalocarid that lived in the Cambrian period. Its two mouth appendages had long bristle-like spines, it had no fan tail, and its short stalked eyes were behind its mouth appendages...

used them to filter

Filter feeder

Filter feeders are animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...

 algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and similar small particles from the water in which it dwelt. They are thought to be homologous with the antennule

Antenna (biology)

Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

 of the euarthropods, or the chelicerae

Chelicerae

The chelicerae are mouthparts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata , and Pycnogonida . Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have...

 of chelicerates.

Two types of great appendage are recognised; the first, the long great appendage such as that seen in the anomalocaridids, resembles a 15–unit leg; whereas the more ubiquitous short great appendage characteristic of the Megacheira

Megacheira

Megacheira is an extinct class of predatory euarthropods that possessed a pair of short enlarged appendages . They were found in marine environments throughout the world from the lower to middle Cambrian, and were important components of several faunas, including the Burgess and Maotianshan...

 is arm-like with a claw-like end. The latter form is a synapomorphy

Synapomorphy

In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...

of the euarthopods and may be homologous with the large great appendage.