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What is one of the first jawless fishes known from the Ordovician Period?

What is one of the first jawless fishes known from the Ordovician Period?

The first complete specimen of a jawless fish with bone, Arandaspis, is known from the Ordovician.

What were some animals during the Ordovician Period?

The Ordovician is best known for its diverse marine invertebrates, including graptolites, trilobites, brachiopods, and the conodonts (early vertebrates). A typical marine community consisted of these animals, plus red and green algae, primitive fish, cephalopods, corals, crinoids, and gastropods.

What organism first appeared in the Ordovician Period?

Starfish, brittle stars, crinoids, and echinoids, all of which have living representatives, first appeared in the Ordovician. In the evolutionary history of animal life this radiation was second only to the “Cambrian explosion” in importance.

What was the very first fish?

The first fish were primitive jawless forms (agnathans) which appeared in the Early Cambrian, but remained generally rare until the Silurian and Devonian when they underwent a rapid evolution.

What did jawless fish evolve from?

Jawless fishes probably arose from ancient, small, soft-bodied filter-feeding organisms much like and probably also ancestral to the modern sand-dwelling filter feeders, the Cephalochordata (Amphioxus and its relatives). The body in the ancestral animals was probably stiffened by a notochord.

Which of the following is a jawless fish?

There are two categories of jawless fish: hagfish and lampreys. Hagfish usually feed on dead or dying fish.

What 2 main types of predators arose during the Ordovician?

Ordovician communities were ecologically more complicated than Cambrian ones. The Ordovician saw the rise of several new life habits, including deep-deposit feeders, mobile epifaunal (superficially attached) carnivores, and pelagic (open-water) carnivores.

What organisms became extinct in the Ordovician Period?

The extinction event abruptly affected all major taxonomic groups and caused the disappearance of one third of all brachiopod and bryozoan families, as well as numerous groups of conodonts, trilobites, echinoderms, corals, bivalves, and graptolites.

What species went extinct in the Ordovician Period?

About 445 Million Years Ago: Ordovician Extinction Its major casualties were marine invertebrates including brachiopods, trilobites, bivalves and corals; many species from each of these groups went extinct during this time.

What is the oldest prehistoric fish?

Haikouichthys, from about 518 million years ago in China, may be the earliest known fish.

What is the most ancient fish?

The early vertebrate Haikouichthys, from about 518 million years ago in China, may be the “ancestor to all vertebrates” and is one of the earliest known fish.

What period did fish evolve?

about 530 million years ago
The evolution of fish began about 530 million years ago during the Cambrian explosion. It was during this time that the early chordates developed the skull and the vertebral column, leading to the first craniates and vertebrates.

When did the first fishes appear?

While there’s an abundance of fish fossils from about 420 million years ago, the ancient fossil record gets scarce farther back at about 480 million years ago, when fish are believed to have first appeared.

What are 3 examples of jawless fish?


  • The jawless fish include the lampreys and the hagfish.
  • Jaws, fins, and stomachs are absent in the jawless fish.
  • Features of the jawless fish include a notochord, paired gill pouches, a pineal eye, and a two-chambered heart.

What are 2 examples of jawless fishes?

What was the dominant predator 470 million years ago?

The big tentacled fellow in the middle and his friends in the background were the dominant predators of that time. These cephalopods were distant relatives of squids and octopi with large, straight shells that could reach nine feet in length! The big one has snared a trilobite with its tentacles.

What animals existed 450 million years ago?

Lobsters and other filter-feeding crustaceans first emerged millions of years before dinosaurs, and in fact the creatures we call horseshoe crabs (more closely related to spiders than modern crabs) appeared around 450 million years ago.

What were the 5 mass extinctions?

Top Five Extinctions

  • Ordovician-silurian Extinction: 440 million years ago.
  • Devonian Extinction: 365 million years ago.
  • Permian-triassic Extinction: 250 million years ago.
  • Triassic-jurassic Extinction: 210 million years ago.
  • Cretaceous-tertiary Extinction: 65 Million Years Ago.

What were the 6 mass extinctions?

Why were there jawless fish in the Ordovician era?

During the Ordovician and Silurian periods — from 490 to 410 million years ago — the world’s oceans, lakes, and rivers were dominated by jawless fish, so named because they lacked lower jaws (and thus the ability to consume large prey).

What is the oldest jawless fish with bone?

The oldest jawless fish with bone is known from 470 million years ago (Arandaspis). It is similar to the oldest complete fossil of Sacabamaspis from the Late Ordovician. The earliest Ordovician fish seem to be relatives (and perhaps ancestral to) the later group of heterostracans.

What is the fauna of the Ordovician period?

Artist’s depiction of the rich fauna of the Ordovician. Animals include, from left: Cystoids, jawless fish ( Sacabambaspis) captured by a large cephalopod ( Endoceras ), Rugose corals, brachiopods, trilobite, gastropod ( Cyclonema), a sea star and coiled cephalopod. Jellies, small nautiloids & graptolites ( Orthograptus) are seen to the left.

What are some examples of jawless fish?

The most notable jawless fish of the Ordovician period were Astraspis and Arandaspis, six-inch-long, big-headed, finless fish that resembled giant tadpoles.