On Sabbatical.

A huge thank you to everybody following Life Before the Dinosaurs and wondering why Art hasn't posted in a while. You guys are the best!

Art is in the middle of a particularly busy school year (third grade is insane) and the blog had to be back-burnered. He's on sabbatical! Art is still studying and studying and studying--it's his favorite thing to do. I'm confident he will be back with a new post soon. Thanks again to everybody!

The Mom

Ctenoimbricata.

Ctenoimbricata (ten-oh-im-bri-kah-tuh) was an early echinoderm that looked a lot like a trilobite. It lived in the Cambrian, and the only two known specimens were found in Spain. It was described by researchers at the Natural History Museum of London and the University of Birmingham in 2012.

Ctenoimbricata was teardrop shaped, with many flat, triangular feeding appendages in the front. Like modern marine detritivores, it may have used its feeding appendages to put sand into its mouth, sort out the food from the sand, and spit out the excess sand. I think it probably would have eaten a small marine worm if it happened to catch one, like today's deep sea sea cucumbers do. 

©lifebeforethedinosaurs.com
Ctenoimbricata crawling on the sea floor

Ctenoimbricata was only 20 millimeters long, so it needed to have defenses. These were in the form of spines all over its body, similar to modern sea urchins. It was also probably slow, like modern echinoderms, and used tube feet to move around. It had hundreds, or maybe even thousands, of these tube feet, which are tiny, clear, gooey sticks, often with a suction cup-like device on the bottom used for moving around. 

©lifebeforethedinosaurs.com

Ctenoimbricata is a very important discovery because it is the oldest fossil that is definitely an echinoderm. The fossil was scanned and reconstructed, and the scientists found out it was bilaterally symmetrical, unlike other echinoderms, which have radial symmetry. This adds to the evidence that echinoderms and chordates may be related. 

©lifebeforethedinosaurs.com
Fossil of Ctenoimbricata

Thanks to Dr. Alien for first telling me about Ctenoimbricata!

References:

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0038296

http://infaunalepiphany.wordpress.com/2012/06/09/from-worm-to-star-primitive-bilateral-echinoderms-from-the-cambrian-of-southern-europe/

http://emilyd47.blogspot.com/2012/06/ctenoimbricata.html

http://www.thisviewoflife.com/index.php/magazine/articles/bilateral-echinoderm-confirms-ancestry

Opabinia vehicle!

endless-swarm posted this video in the comments to my last post. I think it's really amazing that this group of people made a car that looks like Opabinia. It is very impressive, and has one special feature that actual Opabinia did not have...but probably would have liked to have!

Opabinia (Part 2)

Opabinia was a Cambrian invertebrate probably related to today's velvet worms. It was also related to Anomalocaris, which probably sometimes ate Opabinia. 


Opabinia's main food source was presumably worms, which were pulled out of their burrows by Opabinia's long proboscis, then torn up and eaten in its "pineapple ring"-shaped mouth located in a scoop on the underside of the creature's head. Another presumed food source of Opabinia was carcasses, especially of large animals such as Anomalocaris and Hurdia. 


One striking feature about Opabinia is that it possessed five huge eyes. Because of where Opabinia's eyes are positioned, it might have had 360 degree vision. It is thought that the eyes probably only detected motion. 


Opabinia swam by undulating the lobes on its sides. Each side possessed eleven lobes. For a burst of speed, Opabinia would have flicked its fins very quickly, similar to how a modern fish does a burst of speed. But Opabinia had a different fin arrangement than a modern fish. 


Opabinia was two to three inches long and probably swam along the bottom of the ocean. 

©lifebeforethedinosaurs.com
Opabinia searching for food.

Opabinia's closest relative was the Australian Myoscolex. Unlike Opabinia, it had no tail fan, and the eyes closest to the back had long stalks that curved backwards. So Myoscolex basically had eyes on the back of its head. And it needed to have eyes on the back of its head, because Anomalocaris, a top predator, was also present in Australia in the Cambrian, and it would have eaten Myoscolex. 


Opabinia was found on the other side of the world from Myoscolex, in British Columbia. 

©lifebeforethedinosaurs.com
Opabinia (top) compared with Myoscolex (below)

Opabinia also has modern relatives called Onychophora, or velvet worms. They live on land, mostly in Australia, and inhabit wet forests. They normally live in families inside logs in the day, but at night they come out to find food. There are usually up to fifteen velvet worms in a family. Velvet worms usually grow up to about 1-1/2 inches. 


Opabinia is actually quite similar to velvet worms if you look at it the right way. Because Opabinia is now thought to have had legs, if you take away all the fins and the proboscis, leave only two tiny eyes and add antennae, you get a velvet worm. 


Another modern relative to Opabinia is the tardigrade, which looks like a very short, stubby, microscopic velvet worm. One striking feature about the tardigrade is that it is nearly impossible to naturally kill, although it is probably very easy to intentionally kill by smushing it. It can be frozen, heated, and even put into space. Scientists put tardigrades into space without a spacesuit or a jar of air...and they survived!!!

©lifebeforethedinosaurs.com
A modern velvet worm on a forest floor. 

References:


http://rstb.royalsocietypublishing.org/content/271/910/1.short


http://burgess-shale.rom.on.ca/en/fossil-gallery/view-species.php?id=93&ref=i&


http://evolution.berkeley.edu/evolibrary/article/cambrian_06


http://paleobiology.si.edu/burgess/opabinia.html


http://dsc.discovery.com/news/2008/09/09/tardigrade-space.html


http://www.amazon.com/Space-Visual-Encyclopedia-DK-Publishing/dp/075666277X/ref=sr_1_3?ie=UTF8&qid=1342545454&sr=8-3&keywords=the+visual+encyclopedia+of+space

Sacabambaspis.

Sacabambaspis is an Ordovician arandaspid, a kind of primitive armored jawless fish, that has been found in Bolivia in the Andes Mountains. It was about one foot long. Like all fish of its time, Sacabambaspis had no jaws, so its mouth was always open. It had no jaws and it didn't have any teeth either. If it did have teeth, it wouldn't have been able to use them, because it didn't have jaws. All Sacabambaspis ate must have been algae, plankton, and tiny pieces of carcass left behind by large predators such as Cameroceras, Endoceras, and Megalograptus. 


The only fin Sacabambaspis had on its body was the caudal fin, or tail fin. Its relative Astraspis didn't even have that. Scientists used to think that Sacabambaspis had a shark-like tail, but now they know that it had a tail similar to modern jawless fish, a sort of eel-like tail. 


The most striking feature about Sacabambaspis was the shell that covered its head. The armor that covered placoderm heads was more like a suit of armor. But Sacabambaspis had armor that was more like a clamshell. Placoderms had different plates of armor all over their head, which allowed different parts of their heads to move. Ostracoderms, armored agnathans, or jawless fish, had shell-like armor, which was usually two plates, one of the top of the head and one on the bottom. The shell on Drepanaspis, from the Devonian, gradually got smaller as Drepanaspis evolved, to form individual plates on the head, more like a placoderm, except it still had no jaws. 


Sacabambaspis had both of its eyes facing forward, which meant that it had 3D vision. Most other jawless fish did not have this feature. 

© lifebeforethedinosaurs.com
Sacabambaspis on a reef with a trilobite, an orthocone, a crinoid,
and rugose corals encrusted with bryozoans.

Sacabambaspis lived on reefs that were home to creatures such as trilobites, crinoids, orthocones, rugose coral, eurypterids, and bryozoans. At the time, any fish on a Bolivian reef almost had to be Sacabambaspis. There are no other known fish from the same place and time, in Bolivia 460 million years ago, when Sacabambaspis was found. 

© lifebeforethedinosaurs.com

Sacabambaspis, accompanied by rugose corals and bryozoan-encrusted rocks,
viewed from above.

The arandaspid family includes Astraspis, Arandaspis, and Sacabambaspis. They were all from the Ordovician. Astraspis was from North America, Arandaspis was from Australia, and Sacabambaspis was from South America. 

© lifebeforethedinosaurs.com

The arandaspid family: (from top) Astraspis, Arandaspis, Sacabambaspis

Arandaspis was more flattened on the sides than other arandaspids, and it was probably unstable and tilty. It had a rigid shell and was about four or five inches long. 


Astraspis was also about four or five inches long. It had no fins, not even a caudal fin, and a very bumpy shell. I hypothesize that with no caudal fin, it probably mostly slithered across the bottom, and from time to time it could have squirmed around and swam up into midwater to feed on plankton. It could then drift down again to feed on algae and scraps of leftover carcass, which is what it mostly ate. Astraspis is the oldest known North American vertebrate. 




References:


The tail of the Ordovician fish Sacabambaspis


Super Little Giant Book of Prehistoric Creatures


http://en.wikipedia.org/wiki/Sacabambaspis

Dinocaridida.

Dinocaridida is the group which contains anomalacarids such as Opabinia and Anomalocaris. There has been much debate over what kind of animal members of Dinocaridida actually were. They possess jumbled-up features of two groups of modern animals, the arthropods and the onychophorans. They lived on every continent except Antarctica. Only one species has been found in Africa so far, an unnamed Ordovician anomalocarid very similar to Peytoia (formerly Laggania). Very few have been found in Europe. Most are found in North America and Greenland, with notable specimens from Asia too. 

© lifebeforethedinosaurs.com

From top to bottom: Jianshanopodia, Kerygmachela, Pambdelurion. Arrows represent method of capture.

The first Dinocaridids, from the early Cambrian, looked more like onychophorans than arthropods. Some had no eyes, like Kerygmachela and Pambdelurion. Kerygmachela had a tiny mouth, which would have meant it needed to chop up its prey before it ate it. It did that by means of its knife-like claws, which shredded prey. The inward-pointing hooks on the spines would have prevented escape. Although it sounds ferocious, Kerygmachela was only about the size of a human hand. Its relative Pambdelurion, which was the same size as Kerygmachela, was a peaceful filter feeder which captured millions of tiny plankton with its hairy claws, which it then "licked" off with its tiny mouth. On the other hand, Jianshanopodia had a unique method of capture. With a motion of its claws and the opening of the mouth, it sucked small creatures into its stomach. Jianshanopodia was also about the size of a human hand. 

© lifebeforethedinosaurs.com
From top to bottom: Anomalmocaris, Opabinia, Petoyia

Typical anomalocarids from the middle Cambrian Burgess Shale were much more complex, looking like a cross between arthropods and onychophorans. Among these, Opabinia was unique. It had a long proboscis with a claw at the end. The mouth was not on the proboscis, but was actually under the head, as in all Dinocaridids. The proboscis was long and flexible, which helped it reach down worm burrows to grab hapless worms, which it ate. Opabinia was also a scavenger of dead arthropods and other animals, which it was very fit for, because of the flexibility of its proboscis, which enabled it to reach into cracks in the armor of a carcass and rip out chunks of internal organs and flesh from beneath the exoskeleton. It also had five huge eyes, which is not unusual in modern arthropods. Many insects have five eyes, except three of those eyes are tiny. In Opabinia they were all large. 


Anomalocaris was a top predator. It could grow to three, possibly even six feet long. It shattered exoskeletons of trilobites and other arthropods with its two seven-inch claws. Like all Dinocaridids (except Jianshanopodia), Anomalocaris had eleven lateral lobes, which it used for swimming. It would have been very stable, and also able to swim backwards. It could hover motionless in mid-water for a long time watching for prey. When it saw something promising, Anomalocaris would lunge forward with its claws flared out, and then grab the food item. It would then rip it to pieces and eat it. 


Peytoia was a filter feeder. I hypothesize that it rammed predators with its huge head, partially because the eyes and claws were set far back, which could have meant the head was doing something that its eyes and appendages should not be involved in, such as head-butting predators. I also think it could have been a mating display, where the males head-butted each other for the right to mate with the females. This could have been possible because only a few specimens showing the head have been found, and it's possible that all of them were males. I'm not really sure what that huge head was for, I just realize that Peytoia had a bigger head than any other Dinocaridid (except for Hurdia, which had strange headgear that made it look like an arrow). Peytoia also had no tail fin, and when wandering around it probably moved very slowly, although it could have been quite capable of bursts of speed. 

© lifebeforethedinosaurs.com
From top to bottom: unnamed Ordovician anomalocarid from Morocco, Schinderhannes bartelsi, Caryosyntrips

Recently, Ordovician fossils of a Peytoia-like anomalocarid have been found in Morocco. My drawing of this unnamed animal above is based on the pictures of the fossils that I saw. 


Schinderhannes bartelsi is the most recent anomalocarid (in geological time). It had two huge flaps right behind its head which propelled it through the water. It had a stingless spine at the rear and no lateral lobes along its sides. The only fossil was found in Germany. It was only about four inches long and it preyed on animals such as small shrimp and worms. 


Caryosyntrips is a new discovery from the Burgess Shale of the middle Cambrian. The feature that stands out about Caryosyntrips is its claws. Instead of grabbing down, as in Anomalocaris, they pinched together like crab claws. They have been compared to nutcrackers. 




References:


Arthropod origins: http://mzp.cz/ris/ekodisk-new.nsf/1a76d1df1a0e29f0c1256e2800520b9d/9a21746463a798e9c125708f002d7766/$FILE/str.%20323-334.pdf


A giant Ordovician anomalocarid: http://www.nature.com/nature/journal/v473/n7348/full/nature09920.html

http://en.wikipedia.org/wiki/Dinocaridid


http://en.wikipedia.org/wiki/Onychophora

I've been doing my blog for one whole year!

My very first post was on May 15, 2011, when my mom took pictures of my Lego jawless fish and asked me if I wanted to start a blog. And I did! I've been doing this for a whole year. To celebrate the anniversary, I picked five of my favorite creatures that I've written about in the last year, and here they are:


1. Anomalocaris (here and here). Anomalocaris was a giant Cambrian predator related to today's velvet worms. It crushed hard-shelled animals with its two seven-inch claws and its "pineapple ring" mouth. It had eleven lobes along the side of its body which helped it hover and swim in mid-water. It also had no legs. It was at least three feet long, but it was almost definitely no more than six feet. Most of the complete fossils are of juveniles. Coprolites containing bits of trilobites have been found in Australia. I hypothesized that Anomalocaris may have given live birth just like today's velvet worms. 

© lifebeforethedinosaurs.com

2. Opabinia. A four-inch-long Cambrian predator, including its proboscis (three inches long without this appendage). Opabinia used its proboscis to poke around in worm holes and rip chunks of flesh off of carcass. Strangely, Opabinia had five mushroom-like eyes on top of its head, each one as large as the other. It was related to Anomalocaris and velvet worms, and I think it could have given live birth too. Opabinia also had eleven lobes along its sides and, like Anomalocaris, no legs. 

© lifebeforethedinosaurs.com

3. Scyphocrinites. Scyphocrinites was a strange Silurian-to-Devonian crinoid that floated upside down at the surface of the water by means of a balloon-like organ called a lobolith in place of the gripping root-like organs that most crinoids possess. Unlike most crinoids, Scyphocrinites could not purposely move (bottom-dwelling crinoids can un-anchor themselves and drag their bodies across the sea floor with their arms to find a better attachment place). Scyphocritinies could only move with the current. Fortunately, this meant that it was always in the same place as its microscopic food, plankton, which was also being swept around by the current. Scyphocritinies was large, but I can't say how large, because I've never found a source that talks about its size other than that its large. The calyx (body) has never been found attached to the lobolith, but we know the calyx and the loboliths found belong to the same species. The same exact stem has been found attached to the lobolith, and that kind of stem has also been found attached to the calyx.  All the pieces of Scyphocrinites were found in Morocco.

© lifebeforethedinosaurs.com

4. Helicoprion (here and here). Helicoprion was a bizarre shark from the Carboniferous to the Triassic. The only fossils that have ever been found of it are its mysterious "buzz saw" lower jaws, which helped it slice prey such as fish and squid. It is unlikely that Helicoprion ate hard-shelled animals such as ammonites, because if it ate mostly ammonites there would be a lot of broken teeth found in the tooth whorls. Broken teeth are nearly absent in the tooth whorls. And sharks tend to eat a lot. The biggest tooth whorls that have ever been found are about two feet across, which meant that Helicoprion would have been 30 to 50 feet long. A very long shark, which would have meant it needed a lot of food and would have had a monstrous appetite. It must have been a top predator. Helicoprion was related to other eugeneodontids such as Edestus and Ornithoprion. It is not known where exactly in the lower jaw the tooth whorl went, but the most modern idea is that it was embedded in cartilage to make a circular extension of teeth on the lower jaw. This idea also includes that the lower jaw was as long as the upper jaw, and that they were both quite long. Most reconstructions of Helicoprion show that it had little or no teeth in the upper jaw. 

© lifebeforethedinosaurs.com

5. Siphusauctum. Siphusauctum is a weird, newly-discovered Cambrian stalked animal. It looked reminiscent of a ctenophore on a stalk and was a filter feeder that fed on plankton. The body was roughly four inches tall. There is a very small amount of information on this animal because it is so newly discovered. It was found many years ago in the Burgess Shale, but was discovered in the collection at the Royal Ontario Museum in 2012. It was described by Jean-Bernard Caron and Lorna J. O'Brien. 

© lifebeforethedinosaurs.com