Pronunciation: [plˈakə͡ʊdəmˌi] (IPA) 
The word "placodermi" refers to an extinct group of armoured fish. The spelling of this word can be explained using IPA phonetic transcription as "plækəʊ'dɜːmi". The "plac" is pronounced as "plæk" with a short "a" sound. The "o" in "o"dem" is pronounced as "əʊ" with a long "o" sound, while the "i" at the end is pronounced as "iː" with a long "e" sound. The stress falls on the second syllable "derm," making it "dɜːrm."
Placodermi, also known as the "armored fish," is an extinct group of prehistoric vertebrates that existed during the Paleozoic era, approximately 440 to 360 million years ago. The term "placodermi" originates from the Greek words "plax" meaning "plate" and "derma" meaning "skin," referring to their distinctive armor-like external covering.
Placoderms were the first known jawed vertebrates and played a crucial role in the evolutionary history of fish, as they were considered to be a significant step in the development of modern fish and ultimately, other jawed vertebrates, including humans. They exhibited a wide variety of body forms, ranging from small, fish-like species to large, heavily armored predators.
One of the most striking features of placoderms was their bony head and thoracic plates, which provided protection for their internal organs and contributed to their classification as "armored fish." Their jaws were made of bone, allowing for more effective feeding and predation. Placoderms were primarily marine creatures, inhabiting both shallow and deep waters. Some even had paired pectoral fins, suggesting they were capable of limited movement.
Despite their dominance during the early Paleozoic era, placoderms eventually became extinct, leaving no known living descendants. However, they left an indelible mark on the evolution of vertebrates, their fossil remains providing crucial insights into the development of jawed vertebrates and the progression of marine ecosystems over time.
The word "placodermi" is derived from the Ancient Greek words "plax" meaning "plate" and "derma" meaning "skin". In combination, "placodermi" translates to "plate-skinned". This term was coined to describe a group of extinct armored prehistoric fish that lived from the Silurian to the end of the Devonian period (approximately 430 to 360 million years ago). Their bodies were covered in bony plates, which gave rise to their name.
