Matt McLain

Galloanseran cranial development highlights exceptions to von Baer’s laws - EvoDevo The remarkable morphological disparity of the animal kingdom is underpinned by changes in embryonic development across the tree of life; as such, deciphering evolutionary patterns of developmental divergence depends on investigations of different species across a range of comparable developmental stages. Among the most influential ideas regarding such developmental divergences are von Baer’s Laws of Development and Haeckel’s Theory of Recapitulation. Here, we assess several predictions following from these ideas at the tissue-level by comparing skull osteogenesis in representatives of the bird clade Galloanserae. We investigated high-resolution µCT scans of embryonic series for four galloanseran species: chickens and quails, representing Galliformes (landfowl), and ducks and geese, representing Anseriformes (waterfowl). To compare skull osteogenesis across our taxon sample, we devised a skull-specific staging system based on ossification sequences to discretise the process into five stages. During skull osteogenesis, we found that the location of the onset of ossification within each element and the direction of ossification progression were the same in all species in our sample, implying a conserved developmental programme for induction and ossification progression across Galloanserae. Moreover, we found that the appearance of synapomorphies diagnostic of broader clades often overlapped with species-specific ones during osteogenesis. Indeed, many diagnostic features of deep clades, such as osteological synapomorphies of the phylogenetically inclusive clade Galloanserae, appear at surprisingly late stages of development. These observations fail to support several predictions of von Baer’s Laws of Development and Haeckel’s Theory of Recapitulation, instead suggesting what we term a ‘braiding’ pattern of developmental divergence in which degrees of interspecific morphological similarity wax and wane during development as a result of the interplay between developmental constraints and phyletic variation.

Arnaout, B., Brzezinski, K., Chen, A. et al. Galloanseran cranial development highlights exceptions to von Baer’s laws. EvoDevo 16, 17 (2025). doi.org/10.1186/s132...

This summer I had the pleasure of collaborating w/ researchers Naiomi Cookson & Arjan Mann (Field Museum) to reconstruct a flesh-model bust of Cyonosaurus. After getting to meet the holotype, I started roughing out the skull armature. More of the process to follow!
#paleoart

HONE, D. W. E., & PRONDVAI, E.. (2025). The shape, structure, function, and evolution of the pterosaurian uropatagium. Anais Da Academia Brasileira De Ciências, 97, e20250129. doi.org/10.1590/0001...

Extreme armour in the world’s oldest ankylosaur Nature - The ankylosaurian dinosaur Spicomellus afer possessed a tail weapon and uniquely elaborate dermal armour.

If you don't have access to Nature, but would like to read our paper on the new specimen of #Spicomellus, you can read it online at this link with no subscription: rdcu.be/eCJK3

Whelks overwhelm and consume lobsters YouTube video by Christie Wilcox

The most chilling science video ever shot
www.youtube.com/watch?time_c...

Otaria byronia is an absolute beast

art of a pair of meilifeilong on a cliff with a volcano erupting in the far distance

a photograph of the meilifeilong holotype

happy #fossilfriday! this is meilifeilong, a pterosaur from early cretaceous china. the holotype is the most complete chaoyangopterid yet discovered; chaoyangopterids, although smaller, had a similar lifestyle to the related azhdarchids, hunting on the ground
(art by zhao chuang)

New paper day! Phil Bell led a great study on some *INSANELY COOL* titanosaur tracks our expedition found in Mongolia. The scales in particular are extra awesome - they're like little pyramids, and they *may* have helped with scratch digging and/or walking on sandy surfaces!

Adaptations for stealth in the wing-like flippers of a large ichthyosaur - Nature Analysis of a fossilized front flipper of the Jurassic ichthyosaur Temnodontosaurus that preserves details of soft tissue indicates the presence of a serrated trailing edge that would have reduced noi...

Among my favourite marine reptiles are the temnodontosaurs, mostly big, predatory #ichthyosaurs, mostly from the European Early #Jurassic. WHAT were they doing, how were they making a living? An extraordinary new #OA paper in Nature provides some answers... www.nature.com/articles/s41...

I am 💯 down with referring to anything AI related as “clanker” based.

Six sketches showing Phytosaurs. Three sketches on top showing Mystriosuchus and three sketches on the bottom showing Nicrosaurus. There are details of their heads and also of their full body

I’m thinking about some of the coolest reptiles of the Triassic: Phytosaurs! No, these AREN’T crocodiles. They are not even closely related to them. Phytosaurs evolved a body plan similar to crocodilians completely separately from them and WAY before they appeared in the fossil record
#paleoart #art

An illustration of a fighter jet compared to an ostracoderm fish with similar control surfaces, colored in yellow on each.

New publication on how headshield processes in ostracoderm fishes worked like control surfaces on planes to stabilize and maneuver. 🐟🧪

Sanchez-Sanchez V, Sanisidro O, Ferrón HG. Functional aspects of the headshield processes in ostracoderms. Paleobiology. 2025:1-13.

doi.org/10.1017/pab....

This afternoon's job is proofing Spinosaur Tales. It should be out in November in the UK, and North America in Feb 2026. Chock full of illustrations by @markwitton.bsky.social and I even graciously allowed him to write some of the text too.

Now, some thoughts on seeing Aquilops on the big screen! "Our" little dino was one of the stars of Jurassic World, and that was quite an experience as one of the scientists behind the research. (1/n)

Coiled skeleton of a fossil mammal, with beige bone against light gray rock.

The pangolin Patriomanis americana on display at NMNH in DC

#FossilFriday 🤝 #IndependenceDay2025

Adam D. Marsh (2025)
A large silesaurid specimen from Petrified Forest National Park, U.S.A., with comments on large body sizes in latest Triassic ornithodirans
Lithodendron 2: 1–15
doi: doi/10.69575/RPK...
petrifiedforestfieldinstitute.org/lithodendron...

Plate of my book showing 6 species of procolophonian reptiles arranged taxonomically

Plate of my book showing 4 species of lepidosauromorphs and archosauromorphs arranged taxonomically

Reptiles of the Early Triassic Beaufort Group (mostly the Katberg Formation) of South Africa (ca. 251 million years ago)

Sneak peek at two plates from my book (in preparation) about the tetrapods of the Triassic

#paleoart #paleontology #art #reptiles #sciart

🎉 Join us for the 7th International Paleontological Congress in Cape Town! 🇿🇦

Paleontologists from around the world will gather to share discoveries, ideas, and inspiration.

Don't miss this unforgettable event!
🔗 ipc7.site

#IPC7 #Paleontology

Systematics of ornithocheiriform pterosaurs On the systematics and phylogenetic nomenclature of the Ornithocheiriformes (Pterosauria, Pteranodontoidea)

Pêgas, R.V. 2025. On the systematics and phylogenetic nomenclature of the Ornithocheiriformes (Pterosauria, Pteranodontoidea). Palaeontologia Electronica, 28(2):a25.
doi.org/10.26879/20
palaeo-electronica.org/content/2025/5546-systematics-of-ornithocheiriform-pterosaurs

Mounted skeleton of the massive Permian pareiasaur reptile Scutosaurus karpinskii at the American Museum of Natural History

#FossilFriday The Permian pareiasaur Scutosaurus karpinskii @amnh.org

Ancient poop yields world’s oldest butterfly fossils Tiny wing scales suggest the proboscis evolved 100 million years before flowers

Oldest known fossil evidence of lepidopterans (butterflies & moths), from the Triassic (~236 mya) of Argentina! Scales from the wings of these insects were preserved in dicynodont coprolites, & were likely on plants eaten by the dicynodonts. www.science.org/content/arti... #PoopScience 🧪💩🪨🦋

We can dance

For #FossilFriday, we have a fossil from our editor John Whitlock.

This Diplodocus specimen is Carnegie Museum of Natural History (CM) 11161. It is essentially complete, largely undeformed, and has been studied so extensively; making it an exceptionally important fossil for understanding feeding 🦕

Against a light purple sky and yellowish plantscape, two russet-coloured armoured dinosaurs wrestle in wet mud, one having got purchase under its rival to heave it up: will it topple over? Why would ankylosaurs do this? Fighting over resources, like lady ankylosaurs or territory? It's hard to say. Ultimately, animals are a lot like people, Mrs. Simpson. Some of them act badly because they’ve had a hard life or have been mistreated. But, like people, some of them are just jerks.

New #paleoart for #FossilFriday: battling Borealopelta with deep (instead of "high waisted") armour and pigmentation. There's a scientific rationale behind this #ankylosaur #art, which you can read here, along with viewing the hi-res and WIPs of the painting. www.patreon.com/posts/130274... #sciart

3D printed skull sculpture of Barinasuchus arveloi. Facing left with mouth open.

3D printed skull sculpture of Barinasuchus arveloi held in my hand. Facing right with mouth open.

3D printed skull sculpture of Barinasuchus arveloi. Facing right with mouth closed.

3D printed skull sculpture of Barinasuchus arveloi. Facing left with mouth closed.

After a few more small revisions my Barinasuchus skull reconstruction is finally done. Sculpted in #Blender, and here 3d printed at 1/6th scale.

#sciart #paleoart #paleontology

Utahraptor State Park officially opened in eastern Utah. Gov. Cox with the godfather of Utahraptor State Park...Kenyan Roberts (w/ proud dad). The world is starting to recognize that Utah has the best Early Cretaceous terrestrial record in the world. @utahpaleo-ufop.bsky.social

A long-necked dinosaur, silhouetted against a night sky bisected by the delicate misty swirls of the Milky Way, walks through a sea of glowing blue dinoflagellates. A crescent moon occurs just above her tail. She wonders why no one else wanted to come on this memorable night walk, and then remembers that she is a reconstruction by an artist living over one hundred million years in the future, and that she exists only as pixels on screens. She has no permanence, no physicality. But, in being composed mainly of light, she feels a oneness with the glowing organisms at her feet, and the twinkling stars above. "Are we not all transient, temporary expressions of physics?", she thinks. "And for what I lack in body, I exist here, in this setting, in this moment, forever surrounded by two of nature's grandest spectacles." She walks on, her lighter-coloured scales catching the glow of the stars and waves. "Things could be worse", she thinks, smiling at how deeply philosophical her small sauropod brain has turned out to be.

New #paleoart posted to #Patreon for #FossilFriday: #sauropod Atlasaurus walks through glowing phytoplankton on a pleasant Jurassic evening. The hi-res painting, WIPs and scientific rationale for the scene can be found here: www.patreon.com/posts/129695... #sciart

White plaster-covered fossils in the field with brown rocks in the background

Now that seasonal help has arrived, field season has begun in earnest at Petrified Forest. Today we trenched a phytosaur skull and mandibles that have that spent the winter under a tarp. #fossilfriday 🦖🧪

Tropidostoma