Pterygometopidae

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Calliops armatus cephalon dorsal CRF

Pterygometopidae is a family of extinct trilobites that lived from the Middle Ordovician to the Late Ordovician period. Trilobites are a group of extinct marine arthropods that are known for their distinctive three-lobed, three-segmented form which includes a cephalon (head), thorax, and pygidium (tail). The Pterygometopidae family is part of the order Phacopida, which is characterized by their well-developed eyes, pleural spines, and the absence of facial sutures in some members during the adult stage.

Description

Members of the Pterygometopidae family typically possess a semi-circular cephalon that is wider than it is long, with a well-defined glabella (the central lobe of the head) that tapers forward. The eyes of these trilobites are often large and situated far back on the head, providing a wide field of vision. The thorax usually consists of numerous segments, each with pleural spines extending from the sides. The pygidium is small compared to the cephalon and thorax, with few segments.

Distribution and Habitat

Pterygometopidae trilobites were marine organisms that inhabited shallow waters of the continental shelves. They are found in fossil records across what are now North America, Europe, and Asia, indicating a wide distribution that reflects the diverse marine environments of the Ordovician period.

Ecology

Like other trilobites, members of the Pterygometopidae family were likely benthic, living on or near the sea floor. They may have been scavengers or predators, feeding on small organisms. The morphology of their bodies suggests that they were capable of burrowing into the sediment or swimming short distances above the seabed to escape predators or to find food.

Evolutionary Significance

The Pterygometopidae family provides important insights into the evolutionary history and biodiversity of trilobites during the Ordovician period. Their diverse morphological features and wide geographical distribution make them valuable for studying the ecological and evolutionary responses of marine organisms to the changing environmental conditions of the time.

Fossil Record

Fossils of Pterygometopidae are relatively common in Ordovician sedimentary rocks. They are often used by paleontologists to date and correlate rock layers due to their distinct morphological characteristics and the relatively short time span in which they existed.

See Also

• Trilobite
• Ordovician
• Phacopida