Thursday, February 24, 2011

Making silhouettes for PhyloPic

So with the launch of PhyloPic, the free online database of silhouette figures of organisms for use by anyone, there is now a big demand for silhouettes of any and all things that are or WERE alive (that's right they want extinct species too!)


As a few people have asked, here is my relatively hassle free way of converting any picture of a critter into a silhouette. While I'm using a photograph in this tutorial example, you can use this on basically any digital format picture there is. (Just keep in mind that the idea of the PhyloPic site is all silhouettes appearing on it are copyright free. So you can't go bashing together silhouettes off other people's work. Just your own.)

For my tutorial you're going to need graphic editing software. Sadly it'll have to be something a little more advanced than Paint, but not by much. (I just tried to use Paint, but couldn't find a brightness/contrast control... otherwise Paint does everything I'm about to talk about).

Step 0

Open your picture in your graphics program. Easy enough, eh ;)

Note: Yeah okay so I'm not doing a prehistoric critter for this tutorial. I just really wanted to be the first to get in a Laughing Kookaburra. So pretend I'm showing you on my previous Tylosaur/Taniwhasaur.

Step 1
Next using whatever means you have start cutting your critter out of the picture. This is the "hardest" part of the process, and to be honest, it is more just tedious than difficult.
`
Use of either of a magic wand or lasso selection tool should do the trick. I recommending zooming in a bit to make sure your cutting out the precise outline of your critter.
`
I also suggest using layers if you're program supports them. Convert your picture to a Raster layer to make your life easier at the least, but an extra layer or two in the background can come in handy too.
`
I've made my "erased" space red so you can see what I've been doing. With layers you can make a nice contrasting background like I have and than easily change it to white later. In the end you'll want your background white.
`
So after a "hard" 5-15 minutes of cutting your critter out ta-da! One ready to be silhouetted critter.

Step 2

Next we come to the key step, and it is about as easy as breathing (in an oxygen sufficient environment mind you :P).

Using your graphic program Brightness/Contrast controls (or at least something that controls the brightness, depending on your specific software) crank the value into the negative hundred(s) level, and you will be done!

So after these two steps you're done!

What, I told you they were easy.

So have fun creating silhouettes, and let's try to populate PhyloPic's with all the weird and wonderful life of the world (past and present).

Help Out PhyloPic!

There's a new biology/palaeonotology art resource site on the block, and it is pretty neat. Called PhyloPic, this new site collects silhouettes of any and all animals (and plants I believe, though I haven't seen any submitted yet) living or extinct for use by anyone who might need them. Whether they need it for a technical paper or simply an educational or popular project, the idea is that there be a database of freely available images anyone can use.




I personally think this is great (especially as a teacher), and have already thrown in a contribution this morning learning of the site. I present to you my Tylosaurus/Taniwhsaurus, complete with new and improved tail fluke (this is based on direct input and collaboration with a Mosasaur expert I might add).

As this was remarkable easy to create, I set a challenge for everyone who reads ART Evolved to create at least one silhouette for PhyloPic a month. With at least 60 known contributors to our site, that adds up to 700 new critters on their site a year!

If you're interested in helping, but don't think it would be easy to create these silhouettes, I can prepare a quick and easy tutorial on just how, well, quick and easy these are to put together. Let me know if you'd be interested in the comment section.

Saturday, February 19, 2011

Scott Person on recreating Theropods

Changing the Face of T. Rex’s Rear-end: A Guide to Illustrating Theropod Tails

by W. Scott Persons



Art is a lie that helps us realize truth. -- Picasso


Smocks and Lab Coats Should Be Friends


Appearing in this month’s edition of The Anatomical Record is a paper written by myself and my graduate advisor, Dr. Phil Currie. The paper offers a new synthesis and new data on the tail musculature of theropod (the two-legged and mostly carnivorous dinosaurs, like T.rex). A key point the paper makes is that most predatory dinosaurs had robust muscular tails, similar to those of modern reptiles. One muscle in particular, the M. caudofemoralis, appears tohave been supersized in most theropods (though not in deinonychosaurs and modern birds). The M. caudofemoralis is an unusual tail muscle. The skeletal component of a tail is an extension of the vertebral column, and in most theropods the M. caudofemoralis was anchored to the first 15-20 tail vertebrae. Moreover, the M. caudofemoralis was also attached, via a long tendon, to the femur (the upper leg bone). When it contracted, the M. caudofemoralis would have pulled on the leg and swung it backwards. This backwards pull appears to have provided the major oomph in atheropod’s locomotive power stroke. So, a bigger M. caudofemoralis indicates a bigger locomotive oomph and supports higher running speeds, increased endurance, and all aroundgreater athleticism for Tyrannosaurus and its kin. (For more on the M. caudofemoralis checkouta guest post I did for David Hone’s Archosaur Musings back in December: http://archosaurmusings.wordpress.com/2010/12/06/guest-post-bulking-up-the-back-end-why-tyrannosaurus-tail-mass-matters/)




Image 1. A photo of the author measuring the tail of a Gorgosaurus at the Royal Tyrrell Museum of Palaeontology.

The paper in The Anatomical Record discusses the methods used in making thisdiscovery and its implications for theropod physiology, but the final point Dr. Currie and I chose to make was how this new information ought to change the way theropod tails are illustrated.

When Craig Dylke approached me with the idea of doing this guest post and sharing the implications of my research with the paleo-art community, I was delighted at the chance.

Applying the results of new paleontological research to the way we visualize and depict prehistoric life is an important final step in the scientific process, and it is one that is often neglected. For me, paleontology’s ultimate goal is to give our imaginations the power to travel back in time. If that sounds whimsical, you have misunderstood my meaning. Our goal should not be to imagine a fantasy. We should aim to form a vision of the various worlds of prehistory with as much accuracy as possible, using all available evidence as a strict guide . . . and that is
exactly what good paleo-art attempts.

From an educational perspective, it is good practice for paleontologists to make a point of keeping artists informed of new research developments and their implications for the appearance and behavior of prehistoric life (and we should state and explain these implications directly without forcing artists to figure them out themselves). For better or worse, the way the general public thinks about dinosaurs is not directly influenced by scientists, or even by popular sciencewriters. Most people have not read a dinosaur book since they were eight, and even the vast majority of the interested public has never read page one of a scientific research paper. But they have all seen dinosaur art, and it is primarily on art that the public’s conception of dinosaurs is based. So, if you want to improve the public’s understanding, improving paleo-art is the way to do it.

Tail Anatomy 101




Image 2. The tail of Coelophysis.

In most theropods, the tail accounted for over half the animal’s length, so getting its appearance right is non trivial. Before diving into how theropod tails looked, we should briefly cover the skeletal and muscular components of the tail. The skeleton inside most dinosaur tails was made of two kinds of bones: vertebrae and chevrons (see Image 2). The vertebrae were aligned end-to-end all the way down the tail and had four major parts, which are diagramed in Image 3. Chevrons are usually (but not always) narrow wedge-shaped bones. In theropods, the chevrons were positioned below the vertebrae with the upper surface of each chevron straddling two vertebrae and the lower tip of each chevron projecting downward. The skeleton of the tail serves three major functions: it protects the spinal nerve cord, it provides rigidity, and it gives muscles a solid framework for attachment.




Image 3. A vertical cross-section through a typical reptilian tail. Together a vertebra and chevron have a shape like an obese lowercase ‘t’.

Naturally, figuring out what the skeletal portion of theropod tails looked like is the easy part. We can accomplish that just by looking at the fossilized bones. But fossilized muscles are extremely rare. Fortunately, bones do sometimes preserve a record of the muscles that attached to them in the form of surface attachment scares. Attachment scars (see Image 4) may be left both by muscles and muscle septa (thin tissue layers that separate muscles). By combining bone surface observations and knowledge of the muscle arrangement patterns seen in modern animals(thankfully, tail muscles do have a reasonably consistent arrangement across terrestrial vertebrates), it is possible to confidently reconstruct the tail musculature of theropods.




Image 4. Close-up on the tail of Ornithomimus.

Arrows indicate the prominent attachment scar left by the septum that separated the M. caudofemoralis and the M. ilio-ischiocaudalis.

I’ll give you the basics. Tail muscles can be divided into two groups: epaxial (those positioned above the caudal ribs) and hypaxial (those positioned below the caudal ribs) (see Image 3). The hypaxial muscles include the M. caudofemoralis and the M. ilio-ischiocaudalis,and understanding the shape and arrangement of these two muscles is critical to accurately illustrating theropod tails. At the base of the tail (near the hips) the M. caudofemoralis is nestled against the centrums and chevrons and it bulges out laterally from the side of the tail (the way our calf muscle bulges out from the back of our lower leg). But (unlike our calfmuscle) the M. caudofemoralis is covered by another muscle: the M. ilio-ischiocaudalis.The M. ilio-ischiocaudalis attaches to the undersurface of the caudal ribs, raps around the M.caudofemoralis, and attaches to the undersurface of the lower tips of the chevrons. The epaxialmuscles and the M. ilio-ischiocaudalis are continuous all the way to the tip of the tail, but, as mentioned previously, the M. caudofemoralis is not. The M. caudofemoralis usually only extends across a third of the tail, and, as it tapers out, the M. ilio-ischiocaudalis takes over its attachment sites on the vertebrae and chevrons (see Image 5).



Image 5. Top-down view of Tyrannosaurus, with M. caudofemoralis muscles restored and sideview of Tyrannosaurus with all tail muscles restored. (Original skeleton illustration by Greg Paul.)

Finding a Model

In trying to accurately illustrate the tail of a theropod it would be helpful to have a living model or two that could serve as a guide for the correct overall shape. Birds are often the best modern analogue for theropods (after all, as their descendants, birds are technically a group of highly specialized theropods). However, due to the need to reduce weight that is imposed by flight, modern birds only have a short series of tail vertebrae and greatly reduced tail muscles. Multi-ton terrestrial mammals are often another reasonable analogue, but the likes of elephants and rhinos all have relatively tiny, fly-swatter tails. The best tail models for theropod illustrators are the distantly related lizards and (if we remember to ignore the rows of scutes) the more closely related crocodilians. Modern reptiles do have the same basic tail anatomy as dinosaurs. So, when you set to work on the back half of your theropod sketch, take a moment to study a photo of a croc or Komodo dragon.




Image 6. Rear-view of a Komodo dragon.

A word of caution: theropod dinosaurs were a unique form of life, and, as with any analog, modern reptile tails have their limitations. The biggest difference between the average theropod tail and the tails of modern reptiles has to do with the position of the caudal ribs on the basal vertebrae. In reptiles, the caudal ribs tend to be low on the vertebrae, but in most theropods the caudal ribs are positioned higher and may be angled upwards (see Image 7). This means that
the hypaxial tail musculature (particularly the M. caudofemoralis) was relatively more massive in theropods.



Image 7. Comparison between a tail vertebra of an Allosaurus (A) and an Alligator (B). Arrowspoint to the caudal ribs.

Common Mistakes Art involves a lot of imitation, and mistakes made by one artist have a tendency to be copied and perpetuated by others. I’d like to point out three of the most common mistakes madeby paleo-artists when illustrating theropod tails. The artwork I will use as examples are all done by paleo-artists that I have tremendous respect for. Using examples from illustrators who don’t care about accuracy would be far less instructive, and these artists all put great care into their work and obviously try to get the anatomy of their dinosaurs as correct as possible (some of the artists are also accomplished scientists).

1. Where’s the Beef?




Image 8. Top-down view of Tyrannosaurus dorsal silhouette with traditionally thin tail (A) vs. modern Alligator dorsal silhouette with beefy tail (B).

In the wake of the Dinosaur Renaissance, it has become fashionable to depict theropods as dynamic and agile animals (as well it should), but, when it comes to the tail, this fashion has committed an anatomical faux pas. Theropods are often illustrated with tails that are thin and laterally compressed at the base. I suspect this is because such tails appear less bulky, more aerodynamic, and better suited for running. Take a look at the tail of a modern crocodilian or terrestrial lizard and you will see just the opposite. These reptiles have robust tails that budge out past the hips. Sometimes this bulge can be exaggerated by fat deposits(which I suspect theropods mostly lacked), but the majority of this tail bulge is the result ofthe large M. caudofemoralis. With an even larger M. caudofemoralis, most theropods should be depicted with even beefier tails. Ironically, although slim tails may look superficiallyfaster, because the M. caudofemoralis is the primary hind limb retractor muscle, reducing tail girth would have a negative impact of theropod athleticism. If you remember nothing else from reading this, remember that theropod tails should be beefy!



Image 9. Two passing tyrannosaurs depicted with extremely narrow tails. Original image by Greg Paul.



Image 10. A crocodile correctly painted with a tail broader than its hips and a youngAllosaurus incorrectly painted with a tail slimmer than its hips. Original image by James Gurney.

2. Muscle Contours



Image 11. Carcharodontosaurus and Deltadromeus with contours highlighting fictitious tailmuscle arrangements. Original image by Mark Hallett.

Including contour lines that show off underlying muscles can add credibility to an illustration. We may look at it and think: “Wow, that artist must really know his/her anatomy.” But, when it comes to the tail, most artists have just been making stuff up and throwing in contours for muscles that don’t exist. If you look at the tails of most healthy reptiles (the highly specialized tails of chameleons are an interesting exception) you will see that boundaries between individual muscles are usually not visible from the outside. In some reptiles, a single muscle contour can be seen running between the epaxial and hypaxial muscles (see Image 12), so it is not unreasonable to include this in some theropod illustrations (but remember the contour should be faint and relatively higher on the tail).



Image 12. Photo of a young green iguana. Arrow points to the single muscle contour linebetween the epaxial and hypaxial muscles.

3. M. caudofemoralis Sandwich

The M. caudofemoralis has a unique tapering shape and was exceptionally massive in theropods, but it was covered by the M. ilio-ischiocaudalis. Often, the M. caudofemoralis is depicted as a muscular hill sandwiched between two flat muscle zones. Details of the shape of the M. caudofemoralis would not be visible without x-ray vision. Think of a hot dog. The sausage affects the girth of the hot dog, but, looking at it from the side, the bun obscures most details of the sausage’s shape.



Image 13. Aerosteon and Gorgosaurus with robust M. caudofemoralis distinctly visible between two improperly flat muscle zones. Original images by Todd Marshall and Scott Hartman respectively.

Finale Words

To sum up: the tails of most theropods likely resembled those of modern reptiles, with relatively larger hypaxial muscles (and relatively smaller epaxial muscles). At the base, the tails of most theropods would have been as broad or broader laterally as they were tall. At and near the point where the M. caudofemoralis tapered out, the tails would be laterally compressed, and towards the posterior tip, the tails would, as the neural spines and chevrons steadily shrunk, return to being roughly round in cross-section. I would like to conclude by sharing two illustrations created in conjunctionwith the theropod tail research study. One is by Scott Hartman (check-out his web site:http://www.skeletaldrawing.com/), and the other is by Lida Xing (who’s art is also featured in the latest edition of National Geographic). I hope these images will serve as guides for your own illustrations, and I look forward to seeing beefier and better theropod tails in the future.



Image 14. Tyrannosaurus by Scott Hartman with a well-rounded tail.



Image 15. Tyrannosaurus by Lida Xing with a slightly less robust (but still plausibly proportioned) tail.

Thursday, February 17, 2011

Speedpaint; Feb18

Tomorrow you not only get to pick an inspirational post by Andrea Cau but also the humor of google's auto translation.

Spread the word!

Tuesday, February 15, 2011

Art Evolved's Glendon Mellow on Peer Review Radio

Recently I was interviewed by Adrian J. Ebsary for Peer Review Radio, out of Ottawa.  It was part of a series of interviews about palaeontology that includes Gary Vecchiarelli, Brian Switek and paleoartist Ron Maslanka - all in one episode.

You can listen to the podcast at Peer Review Radio #16: Why Palaeontology?

There are also more podcast and video interviews with me speaking about art, science, and fossils on my Media page.


-Glendon Mellow

Trilobite Sculptures


 Trilobite Sculptures by Andrew Scott

Check out Andrew's collection of wonderful trilobite sculptures on his Flickr page and on his blog Bug Factory!  Be sure to check out his "dead trilobites in jars!"

Unicorn Retro-Evolution

Unicorn Retro-evolution by Midhat Kapetanovic
(Click on the image to enlarge it.  Seriously, check out the detail!)

Just a small take on presumed Darwinian branching of the Unicorn's evolutionary tree.  You've got your huge savanna rhino type, a polar musk-ox variety, a mountain goat wannabe and a tiny swamp pony scuttling through the dense vegetation.  Hope you enjoy them!

Best regards from Bosnia and Herzegovina,
Midhat Kapetanovic

Sunday, February 13, 2011

Happy Darwin Day 2011!

Happy Darwin Day!

Here's a Dawinian Round-up from around the paleoblogosphere:

I'll add to the list as I find more Darwin posts!  Have a piece of 202 year old cake! 

Amphibians (Speed Paint by Anthony Contoleon)

Here is another one from lunch time in Australia.
http://scienceblogs.com/tetrapodzoology/2010/12/close-up_to_andrias.php#more

Hope you guys like it,
Cheers
Anthony

Dr. Dromaeosaur (Speed Paint by David Tana)

"Friday Speed Paint! Dr. Dromaeosaur gets frustrated as he grades student papers in his scantily decorated office. Inspired by the post from Dave Hone's Archosaur Musings titled, "What bugged the dinosaurs? Poor research...".

I'm know I'm going to catch some heat for leaving him featherless, but if Jurassic Park taught me anything, it's that the smartest "raptors" didn't have feathers anyway. Plus I only had 30 minutes. Created in Adobe Photoshop CS5 on a Wacom Bamboo Fun tablet."

-David Tana

Friday, February 11, 2011

"What Colour Was Anchiornis?"

Any color you like.

Photobucket

Prepping Gorgosaurus

110211tankew

Today's paint in honor of Dave Hone's Archosaur Musings... although the post referred to is by Darren Tanke. Great stuff... and funny honoring such a fastidious and on-going labor with with a 30 minute speedpaint.

Thursday, February 10, 2011

The May Gallery poll is up!

Time to make your choice on the May gallery. The poll can be found on our right sidebar. You are allowed to make alternate choices (though please only vote once...).

We have also included some new quirky options to try and shake up the gallery format a bit. Please let us know what you think of the time period and/or palaeo-environment specific themes (just as a concept... not necessarily the specific options we've given you for each this time around).

11. Feb; Speed Paint - Archosaur Musings

Tomorrow's Speed takes sight on Dave Hone's Archosaur Musings. So head over and find nice, illustration-friendly headlines and content... her some I've found begging for visual treatment:

Packing them in
the most German Pterosaur ever (tough to beat Dave's collage here)
Darren Tanke's Gorgosaurus preparation
Difficult to buy hats for
or perhaps just a simple speedpaint from a photo.

Tuesday, February 8, 2011

Friday Speed Paint David Tana

Sorry this is totally MY bad that this is late, not David's- Craig



I know it's real rough, but here is my submission for the "speed paint" this week. Thanks again for the opportunity to participate!


"Alligators vs watermelon: the final battle"Inspired by Darren Naish's post from Tetrapod Zoology of the same name, an Alligator mississippiensis takes on a pile of Citrullus lanatus. Created with an HB #2 graphite pencil on notebook paper, done on my lunch break in the office in under 30 minutes.

Best,

David Tana

Hello, I'm David and these are my Dinosaur Valentines

Hey there! I've just been added to the AE roster, and I'm pleased to be here. My name is David Orr, and write the daily dinosaur blog Love in the Time of Chasmosaurs. By trade I am a graphic designer, currently designing book covers for a publishing company. I've also been playing around with my illustration skills, especially in Adobe Illustrator. My first submission to ART Evolved was my Pink Maiasaura back in October, and I hope to have a Terror Bird to submit next month. I'm not a fine artist or fully-trained illustrator, so much of my work is based on my love of the simple aesthetics of nature, the interaction of shape, color, and texture that delights the eye. I think some of this is on display in my WIP set of vector-illustrated birds. As is a stylistic debt to Charley Harper, which I gladly admit.

My wife, Jennie, was struck with an idea recently: that I should do some dinosaur valentines, giving me an opportunity to stretch out a bit and merge some of my design and illustration side with LITC. It was a good idea, and I'm pleased with the results. I think you'll get an idea of my influences and methods. I think they make for a good introduction as I join the AE family. Here's one of the designs, featuring a Carnotaurus and a Triceratops.

Dinosaur Valentines

Head over to LITC to read more about my dinosaur valentines and find links to the printable PDFs (in both all-ages and "naughty" forms). I'm excited to join in here and expect it to spur me to keep working on paleo illustrations.

Monday, February 7, 2011

You know you've been there...

The stigma of paleoart... thought I'd share toady's speedpaint. It just came out.

Sunday, February 6, 2011

Nima analyzes Argentinosaur


Shame on Nima for not posting here himself, his post on Argentinosaurus is massive! Click the mount to zap over...

Friday, February 4, 2011

Dead Bowhead whale says "Ouch"

My Friday Speed : Dead Bowhead Whale says "Ouch"

Speed Paint: Pink-headed duck and Red-crested pochard: who would win in a fight?



Pink-headed duck and Red-crested pochard: who would win in a fight?
Speed Paint in MS Paint by Mo Hassan


On left:
Pink-headed duck
Rhodonessa caryophyllacea (Latham, 1790)
Anatidae; Anseriformes; Aves; Chordata

On right:
Red-headed pochard
Netta rufina (Pallas, 1773)
Anatidae; Anseriformes; Aves; Chordata

Created using MS Paint in under half an hour, 4th February 2011.
Inspired by the title and content of the Tetrapod Zoology post: Pink-headed duck and Red-crested pochard: who would win in a fight?

Not strictly palaeo-related, but who cares? :P

Thursday, February 3, 2011

Friday Speeds

Whoah... almost missed the announcement! But here it is: tomorrow's speed session takes aim at Darren Naish's fantastic blog Tetrapod Zoology. Pick a post and do a speed paint / sketch / sculpt.
He has loads of valuable tidbits, and if you're looking to cut corners with the next Terror Bird gallery, you're in luck.

Wednesday, February 2, 2011

A New Banner

As you'll no doubt notice, instantly visiting our site today, we have a brand new banner here at ART Evolved. Normally such a thing on a blog probably shouldn't warrant too much fuss, but as ours is the accumulation of several people's work I thought I'd point it out. Especially if you wanted to make comments (please do let us know your thoughts on this new intro to our site).

There is a more complete and comprehensive post coming on the concept, story, and art behind the new banner.

The quick version though is it is a piece of art that tries to capture the diversity of palaeo-art and the community here at ART Evolved. While it is a singular piece in a sense now, it is composed of 6 individual pieces by 5 different artists. Whether we were successful or not, it up to you the viewer.

Tuesday, February 1, 2011

Terror Bird Gallery Reminder!

One month until the next Gallery here on ART Evolved:  Terror Birds!
Send in your submissions to artevolved@gmail.com for March 1st.

Here are a couple of examples to drive inspiration!

Phorusrhacos longissimus by Charles Knight (via wikipedia)


Titanis walleri by Impossible Pictures (from Primeval)

I can't wait to see the flock of art you wonderful artists will come up with!