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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

Note the small bivalve preserved near the bottom end of metatarsal IV. Photo credit: Sebastián Rozadilla, Federico L. Agnolin, Fernando E. Novas, Alexis M. Aranciaga Rolando, Matías J. Motta, Juan M. Lirio, and Marcelo P. Isasi, 2016. 🤓🦕🦖

joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

Leaellynasaura. Photo credit: Sebastián Rozadilla, Federico L. Agnolin, Fernando E. Novas, Alexis M. Aranciaga Rolando, Matías J. Motta, Juan M. Lirio, and Marcelo P. Isasi, 2016. The fourth image shows the metatarsals of Morrosaurus antarcticus viewed from behind.

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

Matthew Lamanna, 2019. The third image shows the right hind limb of Morrosaurus antarcticus, viewed front-on. The scaling of the limb bones was based on the Australian ornithopod specimen NMV P186047 ('Junior'), which might be referable to

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

overlap with MACN Pv 19777, the AMNH FARB 30897 phalanx probably pertains to the same Morrosaurus individual. Scale bar: 5 centimeters in a, 1 centimeter in b-m. Abbreviations: clp, collateral ligament pit; lc?, lateral hemicondyle; m, matrix-filled cavity; mc?, medial hemicondyle?. Photo credit:

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

phalanx (AMNH FARB 30897) recovered from the Morrosaurus type locality or a very nearby site by the 2011 AP3 expedition in (h) dorsal, (i) ventral (plantar), (j) proximal, (k) distal, (l) ?lateral, and (m) ?medial views. Given its identical or near-identical provenance and lack of anatomical

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

ornithopod Morrosaurus antarcticus. a, Right metatarsus of the holotype (MACN Pv 19777) in dorsal (anterior) view. b-g, Right pedal phalanx III-1 of MACN Pv 19777 in (b) dorsal, (c) ventral (plantar), (d) proximal, (e) distal, (f) lateral, and (g) medial views. h-m, Distal end of right pedal

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

during the winter suggest that Morrosaurus was well-suited to its seasonally challenging environment. Its skeletal structure also indicates it was a swift runner, which would have been useful in its environment. The second image shows the pedal bones of the early-diverging (elasmarian?)

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

still experienced long, dark, and cold winters. Depictions of Morrosaurus show it adapting to the seasonal cold by digging through snow for sustenance like detritus and rotten bark during winter months. Adaptations like a warm-blooded metabolism and the ability to forage for detritus

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

40 - 50 lbs). It was a herbivorous dinosaur whose diet likely included various vegetation from a variety of ferns, seeds, and flowering plants, including relatives of the water lily. The habitat of Morrosaurus was part of a much warmer, more forested Antarctica than exists today. However, it

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

and the specific name, antarcticus, refers to the continent of Antarctica. The only known specimen of Morrosaurus antarcticus - thought to represent an adult - is estimated to be approximately 4.5 to 5 meters (15 - 16 feet) long, with a suggested weight of 18.14 to 22.68 kilograms (

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

66 MYA. Classified as Animalia, Chordata, Reptilia, Dinosauria, Ornithischia, Ornithopoda, and Elasmaria. The name Morrosaurus antarcticus means "El Morro lizard from Antarctica." The genus name, Morrosaurus, comes from the "El Morro" fossil site where its remains were found,

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

the upper part of the tibia, the underside of the tibia, the upper half of the foot, the bottom of the midfoot, and the top of the first joint of the third toe. Morrosaurus lived during the Late Cretaceous Period, Late/Upper Cretaceous Epoch, Maastrichtian Age 70.6 -

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

Novas, Alexis Rolando Aranciaga Mauro, Matthew J. Motta, Juan Manuel Lirio Marcelo, and Pablo Isasi in 2016. The holotype specimen - labeled MACN Pv 197 - consists of a right hind leg, including the top of the femur, the lower end of the femur,

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

separated by the Prince Gustav Channel - in Antarctica (Snow Hill Island Formation). These remains would be the basis for naming the type species Morrosaurus antarcticus, named and described by Sebastian Rozadilla, Federico Lisandro Agnolin, Fernando Emilio

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

Morrosaurus antarcticus was discovered in 2002 by Argentine paleontologist Fernando Novas. Unearthed from the site of El Morro on James Ross Island - a large island off the southeast side and near the northeastern extremity of the Antarctic Peninsula, it is

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 6h

The first image is a fantastic illustration by the talented artist @lacerdajulio.bsky.social. Long ago in ancient Antarctica, during the Late Cretaceous Period. A Morrosaurus antarcticus curiously stares at its own reflection in a frozen river. The first fossils for

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

Stephen Louis Brusatte, Juan Ignacio Canale, Leonardo Salgado, Diego Pol, and Michael Pittman, 2024. 🤓🦕🦖

joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

posterior centrodiapophyseal lamina; prz, prezygapophysis; poz, postzygapophysis; dp, diapophysis; ns, neural spine; nc, neural channel; f, fossa. Scale bar: 1 centimeter. Photo credit: Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano,

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

Michael Pittman, 2024. The sixth image shows the middle-posterior cervical vertebrae of MPCN-PV 738.27. A, cranial view; B, caudal view; C, dorsal view; D, left lateral view; E, right lateral view. Abbreviations: acdl, anterior centrodiapophyseal lamina; pcdl,

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

prz, prezygapophysis; poz, postzygapophysis; tp, transverse process; vg, ventral groove; r, ridge. Scale bar: 1 centimeter. Photo credit: Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano, Stephen Louis Brusatte, Juan Ignacio Canale, Leonardo Salgado, Diego Pol, and

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

and Michael Pittman, 2024. The fifth image shows the proximal caudal vertebrae of MPCN-PV 738.8. A, cranial view; B, left lateral view; C, caudal view; D, right lateral view; E, dorsal view; F, ventral view. Abbreviations: clas, caudal articular surface;

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

view; G, MPCN-PV 738.2 in lateral view; H, medial view; I, dorsal view; J, cranial view; K, caudal view. Scale bar: 3 centimeters. Photo credit: Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano, Stephen Louis Brusatte, Juan Ignacio Canale, Leonardo Salgado, Diego Pol,

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

Ignacio Canale, Leonardo Salgado, Diego Pol, and Michael Pittman, 2024. The fourth image shows the left scapulocoracoid of MPCN-PV 738. A, MPCA 1290. A, MPCN-PV 738.3 in lateral view; B, medial view; C, cranial view; D, caudal view; E, distal view; F, proximal

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

view; E, proximal view; F, distal view. Abbreviations: g, groove; as, acetabular surface; pf, pubic foot; pa, pubic apron. Scale bar: 3 centimeters. Photo credit: Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano, Stephen Louis Brusatte, Juan

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joshuapaleorojas.bsky.social @joshuapaleorojas.bsky.social · 4d

credit: Jorge Gustavo Meso, Jonah Nathaniel Choiniere, Mattia Antonio Baiano, Stephen Louis Brusatte, Juan Ignacio Canale, Leonardo Salgado, Diego Pol, and Michael Pittman, 2024. The third image shows the left pubis of MPCN-PV 738.4. A, lateral view; B, caudal view; C, medial view; D, cranial

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