Dino Diagnosis of the Day

Time for another edition of Dino Diagnosis of the Day! Remember, these diagnoses are taken directly from the original publication, and any pertinant names have been removed. This is an old dinosaur, so you might not know it right off the bat! And awaaay we go!

"A bipedal saurischian of small size, with strong hind limbs and small forelimbs. The bones are hollow, but with rather thick walls. The lower jaws are long, about equal to the length of the femur, indicating a skull quite large in relation to the size of the body. The theeth are thecodont. There were probably about 23 to 25 presacral vertebrae (the anterior ones are missing), three sacrals and a long tail with perhaps 40 or more vertebrae. The centra of the vertebrae are platycoelous and constricted in their mid-portions. The vertebrae have strong diapophyses, with buttresses beneath them, and rather short, heavy neural spines. The ilium is deep and short, its iliac crest being abbreviated, and produced posteriorly. The acetabulum is deep within the ilium and its upper margin forms a shelf to take the thrust of the femur against it. The pubis is long, about two-thirds as long as the femur, broad and platelike, and the two pubes are joined along their midlines by a long symphysis. The ischium is broad proximally, but narrows to a rodlike bone in its more distal portions. The bones of the pelvis seemingly do not unite firmly, but rather are joined by restricted facets, so that the central portion of the acetabulum is open. The femur is a curved, heavy bone, the head strongly set off from the shaft, with no lesser trochanter, but with a strong fourth trochanter. The tibia is strong and the tibia and fibula are elongated, being slightly longer than the femur. The astragalus and calcaneum are obviously separate, but evidently in life were closely appressed to the limb bones."

It just keeps going on like this. The paper has no short "diagnosis" section, thus I've left off the rest of the paper. But this should be enough to get you started.

Dino Diagnosis of the Day #4

It's not actually a dinosaur. It's also brand-spanking new, so if you haven't heard of it, don't feel bad. It's an incredibly exciting critter which I'm drawing up a tentative reconstruction of and in a short time, I will tell you all about it! But here's the first glimpse...

"Bony, anterior cranial crest formed from the premaxilla; keel-like extension of the anterior part of the mandible; heterodont dentition with large monocuspid teeth in the anterior part and multicuspid (tricuspid, quadricuspid, quinticuspid) teeth in the posterior part of the dentition; diastema in the upper jaw between the premaxilla and maxilla; lingual side of the anterior teeth with heavy and conspicuous bowed enamel wrinkles; multicuspid teeth of the upper jaw more bulbous than the teeth of the lower jaw; multicuspid teeth of the upper jaw aligned in one row and show distinct gaps between the teeth; multicuspid teeth of the lower jaw packed close together causing the orientation of the teeth to slope and laterally overlap; very long, slender (length to diameter shaft ratio: 18.2) and straight humerus, with a subrectangular deltopectoral crest."

You'd think the creature in question is known from dental remains alone, but such is not the case. The diagnosis doesn't even address what I think is the most interesting feature of the animal. Give it a guess or two, kiddies! This is a strange bugger!

Dino Diagnosis of the Day #3

It's that time again. This animal is not a dinosaur, may or may not be along their lineage. Depends on who you ask, I suppose. With that clue in mind, here's the diagnosis!

Small slender-limbed ornithodiran characterized by: low subtriangular skull, twice as broad across orbits as deep, expanded nasal which hides premaxillae and external nares in dorsal view, maxilla with raised anterior margin of antorbital fossa, reduced slit-like upper temporal fenestra, broad quadrangular plate-like parietal, quadrate-quadratojugal bar angled steeply backwards from anteriorly placed glenoid (and posteriorly located braincase and long retroarticular process) and metatarsals I-IV equal in length.

If Chris gets this on the first try, I'm gonna go nuts!

Dino Diagnosis of the Day #2

You know? I have this great post in my head about pterosaur crest diversity. I've even got some of the sketches done. What sad is that I was slammed on my back this past weekend by the flu (or something like it) and this is the first significant time I've been out of bed. Very irritating symptoms: Snotting to no end (my...poor...nostrils), coughing so much my throat is raw, lack of energy, no appetite, mild joint pain, and ridiculous dehydration. And it seems to get worse as the day progresses. At any rate, I'm just too drained to write a real post, so I'm copping out and giving you kind people my second Dino Diagnosis of the Day!

This is a revised diagnosis:

Large theropod with elongate neural spines that are more than 2.5 times corresponding presacral, sacral and proximal caudal lengths of the centra. Lacrimal contracts postorbital; supraoccipital expands on either side of the midline to protrude as a double boss behind the nuchal crest; pleurocoelous fossae and foramina pronounced on all presacral and sacral vertebrae; cervical neural spines have triangular anterior processes that insert into depressions beneath overhanging processes on preceding neural spines; accessory transverse processes on mid-caudal vertebrae.

Go forth to your archives, dear readers, and come back with answers in tow!

Dino Diagnosis of the Day #1

Brian has Picture of the Day, and Darren has...well, Picture of the Day, too. I'm trying something different! Dinosaur Diagnosis of the Day! On occassion I will go into my closet full of paleo papers and pull out the description of some mesozoic dinosaur. I'd like to turn this into a game, as Darren originally did. We'll see how strong a response this maiden description gets.

Ready? Guess the beastie!

"Small to medium-sized theropods, lightly built and bipedal in posture. Fore limb not reduced. Manus long and slender with three functional digits, Digit III moderately divergent and carpus highly specialized with asymmetrical ginglymus on radiale. Hind limb long, pes of moderate length and functionally didactyl. Digit II modified as an offensive or predatory weapon with large, trenchant claw. Digits III and IV of subequal and normal, digits I and V reduced. Eight to 9 cervical vertebrae, 13 to 14 dorsals and 3 to 4 sacrals. Caudal series of ________ highly modified by extremely long prezygapophyseal and chevron processes which rendered the tail virtually inflexible throughout most of its length. Comparable caudal modifications are presumed, but not known, in other taxa referred to the family."

That's all quoted directly from the original description. Give it a shot, folks--who be it?

EDIT: Chris Taylor is our winner, correctly identifying the mystery taxon as Deinonychus antirrhopus. I should have picked somebody a little more derived! I wanted to do a dromaeosaur, but Chris was right in pointing out that, in 1969, these now ho-hum deinonychosaur features were diagnostic back then. Nowadays this description could apply to just about any deinonychosaur, including Troodon, Velociraptor, Sinornitholestes, Buitreraptor, etc. Our ideas of "small to medium-sized" have changed, too. Back in the day, Compsognathus was considered tiny. Deinonychus was 12 feet long and Ostrom considered it "small to medium-sized!"