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What the Colombian fossil lizard fish has in common with the Arkansas saber-toothed herring

Three years ago, a ten year old boy was visiting a monastery in Colombia. Being a curious boy, he looked around at his surroundings. He could have done like others have done for centuries and not paid that much attention to the stones upon which he walked, but he didn’t. He noticed a curious fossil fish in one of the flagstones. Most people, if they noticed it at all, would have simply given it a passing nod of interest. He, on the other hand, took a picture of it and sent it to the local Paleontology Research Center to see if they knew what it was.

Firstly, I amazed they even had a local paleontology research center, most places don’t. Secondly, it is amazing that the boy took the time to bring it to their attention. Thirdly, it is amazing that someone there noticed what they had and brought it to the attention of the needed experts. All these amazing, unusual occurrences have resulted in an article in the January 31 edition of the Journal of Systematic Paleontology detailing the new fossil species discovered by that boy. Sadly, no one knows how to contact him to let him know about the publication. The researchers have his name and email, but have apparently been unable to contact him to give him his copy of the paper about his fish.

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The fish he discovered was named Candelarhynchus padillai, after the Monastery of LaCandelaria near Ráquira, Colombia, where it was found. The stone for the flagstone came from a nearby quarry.  According to the authors of the paper, the rocks in the quarry corresponding to the flagstones were “fossiliferous, finely laminated, light to dark grey, indurated mudstones ofthe lower-middle Tuonian San Rafael Formation…” The rock strata also contained numerous plankton, ammonites, clams, and crabs; so quite a rich fauna. The Turonian is 89.8-93.9 Mya, according to the latest GSA time scale, so we are talking roughly 92 Mya. 

The fossil is excellently preserved, with slabs containing both part and counterpart, meaning that when they split the slab, pieces and impressions were left on both sides. The whole body can be seen, with nice detail around the head, as well as impressions of the soft tissue portions of the fins. At 27 cm (just over one foot), it is a decent-sized fish. It’s a thin fish, with a long skull full of tiny, conical teeth. It was clearly a fast-swimming predator, and likely prey for a lot of larger species.

Credit to Oksana Vernygora 2

The reports on the fish said that it does not have any living relatives. That is true, in a way, but also not. The specific family the phylogenetic analysis placed it in is Dercetidae, an extinct family that all died out in the Cretaceous. However, if we look a bit broader, it is in the Order Aulopiformes. This order is mostly known for a variety of mostly deep water fish known as lizard fishes, which is why all the news reports of this find have said Candelarynchus was a “lizard fish.” Even though it is in the same Order, it is not in the same family as any of the modern lizard fish.

But the title of this post mentioned Arkansas and I have thus far not done so. Vernygora reports that current analyses of fossil aulopiforms include three main families: the Dercetidae, Halecidae, and the Enchodontidae. One of the most prominent Cretaceous fish from Arkansas is Enchodus, commonly called the “saber-toothed herring.”

This is a terrible name because Enchodus has nothing to do with herrings. It was at one time considered part of Salmoniformes, making it closer to salmon. However, more recent analyses have consistently placed it in Aulopiformes, specifically within the Enchodontidae, making it closer to lizard fish. This makes a good deal of sense to me because, if you add the fangs from a payara, commonly known as the vampire fish, onto a lizard fish, you have  pretty good idea of what Enchodus was like.

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Payara. Image credit Exotic Fish Wiki

Fossil lizard fish then were quite abundant in the Late Cretaceous in both worldwide range and diversity. They may not be the most recognized fish today, but they have a long history and make for great fossils that can be found in a lot of places, including southwestern Arkansas.

 

Website Full of Fossils

Southwest Arkansas has a lot of Cretaceous rocks. During that time, Arkansas was right at the border of the Western Interior Seaway. As such, one can find a lot of marine fossils from the dinosaur era, including mosasaurs, elasmosaurs, oysters by the millions, clams, shark teeth, and much more. You can also find shoreline fossils, such as thousands of dinosaur footprints and the occasional bone.

ammonite2If one crosses the border into North Texas, one can find a lot of fossils that are similar to the southwest Arkansas marine fossils. There is a website, called txfossils.com, a Texas resident has put up showing lots of pictures of the fossils found in the area. The pictures are divided into several categories. The first category is for cephalopods, which are mostly ammonoids. They are listed as ammonites, but they are mostly goniatites from what I can tell, although I can not see the suture patterns (the septa, or walls, between body chambers) well enough and most of them to say for sure. Even though most people refer to the entire group as ammonites, ammonites comprise a single subgroup with the larger group called ammonoids known for complex body septa. Goniatites have a simpler wavy pattern. Nautiloids comprise the third group and are known for simple curves forming the septa.

ST3The other categories include gastropods (snails), echinoids (sea urchins), bivalves (clams), coral and bryozoa, petrified wood plants, and bones from vertebrates. The vertebrate bones include a varitey of shark teeth and some teeth from Enchodus, the “fanged herring”. There are also what appear to be turtle shell fragments and some random bits of bone I cannot identify.

There are lots of pictures (the two shown here are from the website) which should give you some idea what you are looking at if you go fossil hunting in southwest Arkansas. Enjoy. As always, if you find any vertebrate material, please let me know. If you find invertebrate fossils you would like identified, your best bet is to contact Rene Shroat-Lewis at the University of Arkansas at Little Rock or Angela Chandler at the Arkansas Geological Survey.

 

Fossil Friday

It’s Friday, time for the answer to Monday’s mystery fossil. Were you able to identify it?

enchodusoceansofkansasThese fossils are from a fish called Enchodus, the “saber-fanged herring.” Teeth of Enchodus are commonly found in the Cretaceous-aged rocks in southwestern Arkansas, especially near Malvern and Arkadelphia in the Arkadelphia and Marlbrook Marl Formations, up into the Paleocene rocks of the Midway Group a bit farther north. In other places you can even find them in rocks of Eocene age, although you will have much better luck in the Cretaceous rocks. At this time, southern Arkansas was shallow to coastal marine. Go to the Bahamas, imagine Enchodus, mosasaurs, plesiosaurs, and plenty of sharks in the water around the islands and you would have a good picture of the landscape back then. They were abundant at the end of the Mesozoic Era and survived the asteroid impact that rang the death knell for many animals, including the non-avian dinosaurs. But they never regained their prominence as a key member of the marine ecosystem, eventually dying out completely in the Eocene sometime around 40 million years ago (the Eocene lasted from 55 to 34 million years ago).

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The fish reached sizes over 1.5 meters, which makes them on the large side, but not really big, considering there were mosasaurs in the same waters that surpassed 10 meters. Still, with fangs longer than 5 cm, they would not have been fun to tangle with. They were clearly effective predators on smaller fish and possibly soft animals like squid. At the same time, fossils have been found showing they were themselves prey for larger predators, such as sharks, the above-mentioned mosasaurs, plesiosaurs, and even flightless seabirds such as Baptornis. Baptornis was a toothed, predatory bird, but as it only reached 1 meter or so, it would have only been able to hunt young Enchodus. So like many of us today, Baptornis was always up for a good fish fry.

Hesperornis, a larger version of Baptornis, and a few Enchodus feeding on some herring-type fish. Picture by Craig Dylke.

Hesperornis, a larger version of Baptornis, and a few Enchodus feeding on some herring-type fish. Picture by Craig Dylke.

Enchodus is often called the “saber-fanged herring,” although it is unrelated to herrings. So what then was it? Herrings are what is known as forage fish, meaning they are mostly prey items of larger fish and other animals. Most of the fish called herrings are in the family Clupeidae in the groups Clupeiformes, which includes such well-known fish as sardines and anchovies. Enchodus, on the other hand, has been placed into the group Salmoniformes, which includes trout, char, and of course, salmon. When one typically thinks of trout and salmon, one doesn’t think of bait fish, they think of the fish that eat the bait fish. Thus, Enchodus would better better described as a fanged salmon (they were a bit large to call them fanged trout).