The placoderms appear in the fossil record during the Silurian, but the apex predator of the ocean that we call Dunkleosteus began to appear in the Late Devonian, near the decline and extinction of all of the placoderms. Lasting about 50 million years, the placoderms were fairly successful while they were around (not as successful as the 400 million year old lineage of sharks of course). The height of the evolution of jaw mechanics of placoderms is very evident in the articulated specimens of Dunkleosteus that have been discovered. The strength needed to open and close the jaw of the heavily armored skull alone was probably quite great. Add into the equation the amount of space available for additional muscle attachment, or simply strengthening the fewest required muscles, and the strength available for closing the massive jaws in a quick decisive snap is very impressive. Capable of up to 7400N of force along the "toothed" edge, the snap of that fish jaw could destroy most other fish in its sea and most likely many small man-made boats currently in the water these days. Part of the anatomy that helps this mechanism achieve the wide range of motion prior to the strong snapping of the jaws is the nuchal gap between the proper skull and thoracic shields.
22 April 2014
The majority of papers on Dunkleosteus are focused on one of two things: either describing and referring new partial specimens or discussing bite force and feeding strategies. There are most likely other paper topics, but they are buried in the search results. In the interest of interesting topics, I have only chosen to share the two newest bite force papers to share. Mechanics and bite force modeling from 2007 are a good way to start. An update to that model and the feeding mechanics of Dunkleosteus appeared two years later in 2009. In a totally unrelated document there is mention of Dunkleosteus in a document by Rebecca Kagle discussing fish evolution.
21 April 2014
Perhaps there should not be, but there are a lot of Animal Planet and BBC clips featuring Dunkleosteus online. That is, of course, because there were so many of those clips in different documentaries aired by those networks. As a gigantic fish that is rather charismatic with the public, Dunkleosteus appears in a lot of popular outlets for both ratings and because of the charisma that it possesses. Ignoring the pseudo-science of most popularized fossil animals in documentaries, these are some pretty interesting clips regardless of the accuracy of the information.
20 April 2014
Davi Blight's illustration of Dunkleosteus attacking some children is pretty awesome, despite being pretty detrimental to the children in the illustration. There are number of fairly good information sites but today only About and Enchanted Learning are being referenced in that respect today. The Enchanted Learning page doubles as a coloring sheet online for Dunkleosteus as well. There is also a page available from a worksheet website, it appears as seen below:
19 April 2014
18 April 2014
In the continuing tradition of April, this week is another deviation from the norm. Rather than venturing back into the Mesozoic and staying on land, this week the plan is to slide off the beach and back in time even further, to the wild seas of the Late Devonian. 380 to 360 million years ago armored fish roamed the oceans of Earth. Many of these fish were still jawless animals that would barely be recognized as fish, but the earliest jawed fishes were clearly taking control of the seas by the Late Devonian. One set of the larger jawed fish, a truly charismatic mega-fish genus, was Dunkleosteus. Named for David Dunkle and the bony head that is the most commonly found fossil associated with the animal, Dunkleosteus was a hypercarnivorous fish capable of eating its way through the ocean with sharp bony ridges on its jaws and a powerful bite. As far as fish go this is a well known fossil and a rather well documented fossil at that. Who knew a fish would be so fun or interesting?
17 April 2014
Desmatosuchus is a popular model in videos and games, old and new. It appears in dinosaur encyclopedias, despite not being a dinosaur. It also appears as an inspiration in Spore a few times. This one is the best and looks about as real as any Spore model has looked. However, the most ridiculous but entertaining and probably also the funniest Desmatosuchus model in all of video games is that found below: