Cephalaspis

Cephalaspis is an extinct genus of early jawless fishes from the Devonian, distinguished by a broad, flattened bony head shield.

Osteostraci: Osteostraci are an extinct group of armored jawless vertebrates with bony head shields and paired pectoral fins. Cephalaspis belongs to this group, whose shared anatomy places it among early vertebrates.
Cephalic shield: A cephalic shield is a broad bony covering over the head of certain extinct fishes. This flattened armor is Cephalaspis’s defining anatomical feature.
Devonian: The Devonian is a geological period spanning about 419 to 359 million years ago. Cephalaspis lived during this period of major diversification among fishes.
Cephalaspis lyelli: Cephalaspis lyelli is a species of Cephalaspis named from Devonian fossils in Scotland. It is the type species anchoring the genus name.
Ostracoderms: Ostracoderms are a historical grouping of extinct, armored jawless fishes. This broad grouping provides the traditional context for Cephalaspis and other armored jawless forms.
Endoskeleton: An endoskeleton is an internal supporting framework made of bone, cartilage, or other tissues. The shield covered the head while internal skeletal structures supported the body.
Lower Devonian: The Lower Devonian is the earliest epoch of the Devonian Period. Important Cephalaspis fossils come from Lower Devonian deposits.
Cephalaspis pagei: Cephalaspis pagei is a species assigned to the Devonian genus Cephalaspis. Its fossils contribute to comparisons among species within the genus.
Vertebrate: A vertebrate is an animal with a backbone or an ancestral vertebrate skeleton. Cephalaspis belongs to the early history of vertebrates, before jaws evolved.
Lateral line: The lateral line is a sensory system that detects water movement and pressure changes. Canals in the head shield preserved sensory structures associated with detecting nearby motion.

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AgnathaBroader topic: Its armored head illustrates the varied body forms of early agnathans.