derived-centrosaur

[derived-centrosaur]

^ blame this dude for the connects

That area is your choanae, your internal nostrils. And Kenichthys here is the one to blame for why they're inside your mouth rather than below your eyes.

Most fish have 2 pairs of nostrils; 1 front pair to let water in, and a back pair to let water out. Our ancestor here is the transition point where the rear nostrils went from outside the mouth to inside. It's rear nostrils are in the tooth-row! As for what ecological pressure made that arrangement advantageous I have no idea. I'm no fishologist but if I were to hazard a guess it may have something to do with being able to force water through the nasal sack via the mouth or gills rather than just swimming

It's possible to get ham stuck in your nasal no-ham zone because evolution doesn't make animals perfect, it makes them good-enough. And at one point having your 2nd nostrils in line with your teeth was good enough.

Sources:

Zhu, M. & Ahlberg, P. E. (2004) The origin of the internal nostril of tetrapods. Nature 432, 94-97

Janvierre, Phillipe (2004) Wandering Nostrils. Nature 432, 23-24

The human body is such bullshit, I hate having to google shit like "why am I having stress symptoms when there are no sources of stress in my life".

[derived-centrosaur]

He's gorgeous!

It's interesting to see how our interpretations of the facial integument have changed. On this guy they have the prominent jugal flange buried within the soft tissue, and the mouth has no cheeks but rather lips that go all the way back (with maybe a bird-like rictus but not sure). The epiossifications of the frill are also buried within the skin.

Our understanding of all these points have changed quite a bit in the last 87 years, and will no doubt change in the next 87 years.

I don't know where I'm going with this, I just thought it was a cool little peek at old ideas!

Today's Exhibit of the Day is a blast from the past! This archival image, snapped in 1938, depicts Museum preparators sculpting a model Triceratops. This large herbivore could reach lengths of 28 ft (8.5 m). The model pictured here isn't on display today, but Triceratops fans can spot a fossil skeleton in the Hall of Ornithischian Dinosaurs.

Plan your visit!

Photo: AMNH Library / Image no. 315711

[derived-centrosaur]

The blood work:

Yeah, the doctors ran some blood work and discovered I was actually the Thing all along. No, I don't know if my insurance will cover it

[derived-centrosaur]

Not a new find, but new to me!

Fossilized cypress amber containing an aphid found attached to the jaw of a Prosaurolophus

McKellar, R.C., Jones, E., Engel, M.S. et al. A direct association between amber and dinosaur remains provides paleoecological insights. Sci Rep 9, 17916 (2019). https://doi.org/10.1038/s41598-019-54400-x

[derived-centrosaur]

i have never felt more seen than traveling with geo students because i walked out of a highway rest stop bathroom to find my buddy crouched over a line of stone tiles in the middle of the hallway and it's like. yeah you gotta check if that floor is granite. let me join you.

[derived-centrosaur]

God I love field geology!

year 2, semester 4, metamorphic petrology field trip

it's a good thing I love walking. Otherwise I'd hate this more than anything.

36°C heat, with only the sun and ourselves to keep us company, we started walking up a slope toward the large marble quarry that Penteli is known for. Same marble that built the great monuments of ancient Athens, of course. On the way up we stop to look at a good outcrop of (ortho)gneiss from a metamorphosed granite, a sample of which is here on the left, rich in mica and thinly banded and sparklier than the night sky, metamorphic petrology has so cooked us that we all saw it's green and schistose and called it greenschist, lol.

Greenschist we did find further up the path, though it's mixed with marble, and we got told the (newfound) big of geology wisdom that, actually, that term is pretty much useless due to the sheer amount of protoliths that can spawn it rendering the term kind of too vague. So this is actually a basaltic intrusion, metamorphosed to the greenschist phase (thus a "metabasalt"), turned schistose due to stresses, and bundled together with some nice white marbles, that metamorphosed alongside them.

The views in and from that quarry are beautiful, if only Mt. Penteli wasn't literally the most fertile ground for fires it'd be greener.

The metabasalt intrusions ultimately ruin the market value of the marble, so the quarry was abandoned. A student doing her dissertation, however, told us about its metamorphosis. The highest temperature reached was 350°C at 6-8 kbars, very close to the blueschist fascies and so in one sample they even found blueschist minerals like glaucophane. Greece is today where the ancient Tethys ocean once laid, and many terranes were subducted into forming the landmass of today.

We then went on a 5km hike up Mt. Penteli on a quest to see the general geology of the area. Essentially (and reductively,) the mountain is like a large anticline fold or an upside down U, with orthogneiss as the lowermost layer and strata of marbles and metapelite schist above. Of course, it's more complicated. Faults and folds have made the anticline nigh unrecognisable, the metapelites vary wildly in schistosity and they often mix with the marbles to form the sparkliest rock you'll ever see, a metamorphosed marl, and the basalt intrusions from earlier show up either schistose or massive or granular, along with dikes of quartz and calcite, and interspersed are pockets of more gneiss.

The climb to the (almost) top was beautiful, although doing it by foot at this weather sucked. The sun blazed unwaveringly and the view was stunning.

[derived-centrosaur]

Last day? Hmmm...

Well, one of these two series are getting one last go

or

either way, buckle up we're gonna be while

What would you do if today was your last day?

[derived-centrosaur]

I had to see what the all the fuss was about, and yeah. Them spiders are very shaped and wonderfully weird! I also found out they've been around since the Jurassic, soooo... I felt compelled

A female Patarchaea muralis climbs through the needles of a Sequoia. China, 160 million years ago.

Paul A. Selden, Huang Diying, and Ren Dong "Palpimanoid spiders from the Jurassic of China," The Journal of Arachnology 36(2), 306-321, (1 August 2008). https://doi.org/10.1636/CA07-106.1

i just rediscovered the pelican spider. give me 1-2 business days to stop laughing at how they're shaped and ill be normal again

[derived-centrosaur]

Reblogging because in addition to being an excellent dove nest, it's also a great view of the very weird nose of Triceratops

Another banger from /r/stupiddovenests - at least the tag is appropriate this time

[derived-centrosaur]

Things that probably happened some time during Fellowship of the Ring: Merry and Pippin tell Boromir things about hobbits, but as a game of "one of us only tells the truth, the other one only lies", and Boromir has to figure out which one is which. Both Aragorn and Gandalf smile knowingly at the things the hobbits claim, but they're not telling. Gimli will argue that everything they're claiming sounds like bullshit, but there is no claim so wild and outrageous that Legolas wouldn't contemplate that it could plausibly be true.

The only thing that keeps Sam from interrupting and telling everyone which claims are outright lies and which ones have been taken so out of context that they sound like bullshit is the fact that Frodo clearly finds this amusing, and Sam can't ruin something that can still get a little fragile smile out of him.

[derived-centrosaur]

Dromiceiomimus brevitertius

A male in breeding plumage takes shelter from the sleet of a spring coldsnap

The second of my Horseshoe Canyon series. I didn't have any particular knowledge of ornithomimids before this piece and I think I might actually know less now that I've completed it. Specifically, this taxon in particular has been problematic for nearly it's entire existence. Originally it was named as a new species of Struthiomimus, and later given it's own genus by Russell in his review of the ornithomimids of Alberta. One of his chief characters for distinguishing this taxon was the ratio of tibia to femur length. This has proven very problematic as this ratio can be affected by individual variation and/or growth stage and subsequently Dromiceiomimus has been subsumed into Ornithomimus by various authors. Though the issue of whether it's synonymous with O. edmontonicus or a valid species within Ornithomimus is not agreed upon even by them. The most recent publication I could find was the Macdonald and Currie (2019) description of a near complete specimen. Therein they run a series of tests to see if the limb ratio is even a valid character, and to my surprise it seems to be so. Of the tested taxa (Dromiceiomimus, Ornithomimus, Struthiomimus, and Gallimimus) all kept a consistent ratio of tibia/femur length across absolute sizes, and therefore the ratio is independent of growth stage at least, suggesting that it could be a diagnostic character (Gallimimus is a small outlier, it had a slight negative allometry, the tibia shortened in comparison to the femur as the specimens got bigger). Combining this with subtle features of the hand and claws they reasoned that Dromiceiomimus was distinct at both the specific and generic levels.

As for depicting it, my best sources were the photos of the fossil from Macdonald and Currie (2018), the skeletal diagrams and thigh muscle reconstructions provided in Russel (1972), the "Ornithomimus brevitertius" skeleton in Paul (1989), and the image of the holotype pelvic girdle provided in Parks (1926). The integument of Ornithomimus has been fossilized in a couple specimens described in Zelenitsky et. al. (2012) and van der Reest, Wolfe, & Currie (2015). given the taxonomic issues, I figured the Ornithomimus integument would be appropriate. What surprised me about the integument was the wings. Specimen TMP 1995.110.1 preserves on its ulna carbonized traces of feather shafts. These traces disappear towards both the proximal and distal ends, meaning that the wing (pennibrachium of their terminology) would have been limited to the forearm and wouldn't continue onto the hand and 2nd finger, nor up to the shoulder as is the case in more derived maniraptors. It feels like a cardinal sin to depict dinosaur wings that way, but that's what the evidence shows for Ornithomimus at least.

The composition, colors, and pose were all inspired by Poodonkis (and if you get the reference maybe take something for your back pain). My challenge was to make him believably pink and spotted and to have him be 'snowed in.' I eventually settled on the idea that the bright pink would be male breeding plumage and since bullfinch, pine grosbeak, and pink headed fruit doves manage the color without filtering crustaceans like flamingoes or spoonbills I figured it could be justified. The spots could be either camouflage like a northern flicker or display like a peacock pheasant, so I done a little of both. The 'snowed in' was tougher, luckily there have been some determinations of paleoclimate for the Horseshoe Canyon Formation, most relevant here are the paleosol samples of Quinney et. al. (2013). Most of the specimens referred to Dromiceiomimus are from the Tolman Member of the formation, which was deposited in a cooler and drier interval. The mean annual temperature and precipitation determined by Quinney et. al. was comparable to those of modern Belgium and Luxembourg, which gives us a rough ballpark to play in. Close enough that I think a cold spring could reasonably produce a sleet storm, not quite a snow-in but close enough for the composition.

References:

Macdonald, I., Currie, P. J. (2018) Description of a partial Dromiceiomimus (Dinosauria: Theropoda) skeleton with comments on the validity of the genus. Canadian Journal of Earth Sciences 56: pg. 129-157. doi.org/10.1139/cjes-2018-0162

Russell, D. A. (1972) Ostrich Dinosaurs from the Late Cretaceous of Western Canada. Canadian Journal of Earth Sciences 9: pg. 375-402.

Paul, G. S. (1989) Predatory Dinosaurs of the World, Touchstone Simon & Schuster. pg. 391

Parks, W. A. (1926) Struthiomimus brevetertius - A new species of dinosaur from the Edmonton Formation of Alberta. Transactions of the Royal Society of Canada, series 3. 20(4), 65-70 (digitized, pg. 949-955)

Zelenitsky, D. K., et. al. (2012) Feathered Non-Avian Dinosaurs from North America Provide Insight into Wing Origins. Science 338: pg. 510-514. DOI: 10.1126/science.1225376

van der Reest, A. J., Wolfe, A. P., Currie, P. J. (2015) A densely feathered ornithomimid (Dinosauria: Theropoda) from the Upper Cretaceous Dinosaur Park Formation, Alberta, Canada. Cretaceous Research 58: pg. 108-117. doi.org/10.1016/j.cretres.2015.10.004

Quinney, A. et. al. (2013) Palaeoenvironmental and palaeoclimatic reconstruction of the Upper Cretaceous (late Campanian-early Maastrichtian) Horseshoe Canyon Formation, Alberta, Canada. Palaeogeography, Palaeoclimatology, Palaeoecology 371: pg. 26-44. doi.org/10.1016/j.palaeo.2012.12.009

[derived-centrosaur]

My two yr old is looking through a book about prehistoric art and she saw a picture of those cave painting of hands and she held up her own and said "hand!" And I gotta be honest. That hit

[derived-centrosaur]

According to my computer's taskbar, it's dinosaur day apparently. So here's some dinosaurs!

A Ceratosaurus meets a Brachiosaurus pair at the watering hole

This is an old pen-and-ink drawing I done at my old CNC job (~2017ish). There was a lot of downtime while the machine ran and there were a lot of read-sheets printed when dialing in parts, so I had a perfect way to kill some time.

Also, Happy Pride Month!

❤️����💛💚💙💜🤍🩷🩵🤎🖤

[derived-centrosaur]

'Badlands? I think they're quite 'good' actually.'

[derived-centrosaur]

Pachycephalosaurus with a bunch of foliage entangled in his horns.

A less serious and less polished piece. The leafy crown is based on a behavior elk, red deer and fallow deer do.

[derived-centrosaur]

Spotted this cool caterpillar at the jobsite a couple days ago and snapped a pic before I had to get back to digging. I've only ever seen caterpillars like this twice before and was wondering what it is? Which butterfly does it become?

Found in Iowa

Cute lil child. Looks like a zebra swallowtail, Eurytides marcellus. Adults look like this:

Photo by gaudettelaura

[derived-centrosaur]

Rewatching Prehistoric Planet and i just...really fucking love the velociraptors at the beginning of episode 3. like it actually makes me tear up.

The velociraptors are hunting some pterosaurs on a steep cliffside, and, just on the approach, you can see the velociraptors using their wings and tails to navigate their surroundings. they flap a little to get some extra height, they're very agile and their jumps are very precise... it's cool to see.

and all that's just foreshadowing for later, when they're being attacked by the flock and the female grabs their kill and fuckign DIVES DOWN THE SIDE OF THE CANYON, using her wings and tail to direct and control her fall down the cliffside and successfully make her escape.

what she's doing is objectively not flying. it's not even gliding. it's 100% falling...but it's skilled, graceful, and, above all else, controlled falling. falling with purpose.

You can see how this behavior might lead to flying eventually, and that's unbelievably cool, but also like... it was really cool to see someone finally look at raptors and say, hey, this isn't just a prototype bird. this is a fully functional animal whose body plan works right now, too. Here's how.