Million Years of Fish Evolution. Compared to dinosaurs, mammoths and saber- toothed cats, fish evolution may not seem all that interesting- -until you realize that if it weren't for prehistoric fish, dinosaurs, mammoths and saber- toothed cats would never have existed. The first vertebrates on the planet, fish provided the basic . The most famous of these, Pikaia, looked more like a worm than a fish, but it had four features crucial to later fish (and vertebrate) evolution: a head distinct from its tail, bilateral symmetry (the left side of its body looked like the right side), V- shaped muscles, and most importantly, a nerve cord running down the length of its body. Because this cord wasn't protected by a tube of bone or cartilage, Pikaia was technically a . Haikouichthys is considered by some experts- -at least those not overly concerned by its lack of a calcified backbone- -to be the earliest jawless fish, and this inch- long creature had rudimentary fins running along the top and bottom of its body. The similar Myllokunmingia was slightly less elongated than either Pikaia or Haikouichthys, and it also had pouched gills and (possibly) a skull made of cartilage. You can recognize most of these prehistoric fish by the . Both of these species made their living by bottom- feeding in shallow waters, wriggling slowly above the surface and sucking up tiny animals and the waste of other marine creatures. Their Silurian descendants shared the same body plan, with the important addition of forked tail fins, which gave them more maneuverability. If the ? The answer is that, hundreds of millions of years ago, vertebrates were far from the dominant life forms in the earth's oceans, and these early fish needed a means of defense against giant . One development, which wound up going nowhere, was the appearance of the jawed fishes known as placoderms (. These were essentially larger, more varied .
The chondrichthians included prehistoric sharks, which went on to tear their own bloody path through evolutionary history. The osteichthyans, meanwhile, split into two further groups: the actinopterygians (ray- finned fish) and sarcopterygians (lobe- finned fish). Ray- finned fish, lobe- finned fish, who cares? Well, you do: the lobe- finned fishes of the Devonian period, such as Panderichthys and Eusthenopteron, had a characteristic fin structure that enabled them to evolve into the first tetrapods- -the proverbial . The ray- finned fish stayed in the water, but went on to become the most successful vertebrates of all: today, there are tens of thousand of species of ray- finned fish, making them the most diverse and numerous vertebrates on the planet (among the earliest ray- finned fish were Saurichthys and Cheirolepis). The Giant Fish of the Mesozoic Era. No history of fish would be complete without mentioning the giant . The most famous of these giants were the Jurassic Leedsichthys, which some reconstructions put at a whopping 7. Cretaceous Xiphactinus, which was . A new addition is Bonnerichthys, yet another large, Cretaceous fish with a tiny, protozoan diet. Bear in mind, though, that for every . The list is nearly endless, but examples include Dipterus (an ancient lungfish), Enchodus (also known as the. AS THE SUN set over Lake Eyasi in Tanzania, nearly thirty minutes had passed since I had inserted a turkey baster into my bum and injected the feces of a Hadza man. The domestic cat (Latin: Felis catus) is a small, typically furry, carnivorous mammal. They are often called house cats when kept as indoor pets or simply cats when. Smilodon is an extinct genus of machairodont felid. It is one of the most famous prehistoric mammals, and the best known saber-toothed cat. Although commonly known as. Pet food made from quality North American ingredients backed by our 'No Bad Anything' promise and unique small-batch production for superior control.
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