Just a couple of quick sketches I did over the weekend.

First is my entry into the #DarwinTrain drawing chain on Facebook - an aquatic denizen of planet Darwin IV (from Wayne Barlowe's "Expedition" book). Next, is a sketch I did for Scott, taking a crack at a character design for an on-going project.

Day of the Dimetrodon! I posted the top sketch to Twitter after reading a 2012 paper on Dimorphodon sail morphology, and decided after receiving some input on Facebook from some fellow artists to create a few different versions.

Tonight's serving of #sciart - three reconstructions of some of my favorite fossil critters. First up, Helicoprion with her modern relative, the Galapagos ratfish. Second, an outdated reconstruction of Thallattosaurus from the side and top, after the original Merriam fossil sketch. Last, we have a troodon with corvid-esque feather patterns from a much larger piece I've been working on for the past couple of years.

Day three (or should that be "pthree"?) of the #Sciart #Tweetstorm - a little late. This day's sketchdump includes two character design roughs for an animation project on the back burner tentatively titled "Flapling" which chronicles the first tentative flight of a newly hatched rhamphorhynchus.

More entries for the #Sciart #Tweetstorm - three works in progress for Wednesday.

First up is a lone Nanuqsaurus that will be used in a few ideas and projects I have on the back burner. Secondly, a layout for a piece depicting the paleoenvironment of Alaska's North Slope during the Late Cretaceous period, with a pint-sized tyrant realizing he blundered into the wrong part of the Colville River delta. Last, a pair of azhdarchid pterosaurs pause for a drink in Denali, leaving their footprints along the side of a stream.

Last year, the authors of the Symbiartic blog on ScientificAmerican.com -- Glendon Mellow, Kalliopi Monoyios, and Katie McKissick -- summoned an epic storm of amazing and informative scientific artwork on Twitter with the