| Biologists could examine the many living animals that represented stages in the transition from the invertebrates to the earliest jawless fishes. |
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| These were jawless, armored fish informally called ostracoderms, but more correctly placed in the taxon Pteraspidomorphi. |
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| When the fossilized lamprey lived, there were probably many types of jawless vertebrates. |
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| In short, this analysis finds that conodonts are more derived than any of the living jawless vertebrates. |
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| In traditional classifications, the hagfish, lampreys, and extinct armored jawless fish are grouped together in the paraphyletic Class Agnatha. |
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| At a quick glance, jawless fish such as the lamprey above don't appear to have much in common with jawed fish or any other back-boned creature. |
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| Litman next plans to look for novel immune genes in jawless vertebrates, such as lamprey and hagfish. |
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| Most jawless species went extinct long ago and are known only from the fossil record. |
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| In modern classification schemes, living vertebrates consist of two main groups, the jawless Agnatha and the jawed Gnathostomata. |
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| The earliest fossil vertebrates belong to a group called the Agnatha or jawless vertebrates. |
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| The branchiomeric musculature of more primitive jawless fishes would probably have been similar for each of the gill arches. |
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| Some 450 million years ago, both jawed and jawless vertebrates began relying on cells called lymphocytes to support the burgeoning adaptive immune system. |
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| The hagfish, together with lampreys, are living representatives of the jawless vertebrates and are considered to be the most evolutionarily ancient vertebrates. |
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| And while jawless vertebrates were present in the Cambrian, it was not until the Ordovician that armored fish became common enough to leave a rich fossil record. |
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| Neither of these jawless fish has a bony skeleton, but most of the fossil groups listed on the cladogram had a fairly extensive covering of bony plates. |
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| The oldest unequivocal chordate remains come from the Lower Cambrian of south China, where small jawless fish similar to present-day lamprey and hagfish occur as part of the Chengjiang Biota. |
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| It comes from the Pacific hagfish, a jawless fish which is also known as the slime eel. |
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| Early fish from the fossil record are represented by a group of small, jawless, armored fish known as ostracoderms. |
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| He glanced across her at the jawless, pie-faced woman soon to be her mother-in-law, whose owlish eyes were fixed askance upon their hands. |
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| The bony fish have three pairs of arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven. |
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| Haikouichthys is one of three species of jawless fish to be found in the Early Cambrian period. |
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| Today, the only jawless vertebrates are lampreys and hagfishes, whereas jawed vertebrates number more than fifty thousand species, including ourselves. |
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| Jawless fishes and placoderms were also affected, although many placoderm lineages survived quite happily until the end Devonian. |
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