The head and (long) neck of Miragaia longicollum
Credit: Zachary Miller, When Pigs Fly Returns

• New Dinosaur: Miragaia longicollum
• Name Means: Long-neck from Miragaia (or, alternately, “long-necked wonderful goddess of the Earth”)
• Relations: Dacentrurine stegosaur
• Holotype: ML 433, partial skull and mostly complete skeleton from the arms forward
• Referred Material: ML 433-A, parts of the pelvis and dorsal vertebrae from a juvenile
• Location: Miragaia, Portugal
• Age: Late Jurassic (~150,000,000 years ago)
• Length: ~3.5 meters (about 11.5 feet)
• Info:
  Top: the fossils of Miragaia longicollum.
  Bottom: Skeletal reconstruction with human holding a 2m-tall scale bar
  Credit: Dr. Octavio Mateus, from Everything Dinosaur
• I’m very late in getting a post up about Miragaia, and there are several good posts out there already about this unexpected fossil and its unusual anatomy. So I’ll just say, “Lookit that long-necked critter!” and encourage interested readers to download the paper and check out the posts listed in the “Further Reading” list for analysis and commentary on this impressively cervical stegosaur.
• Reference: Mateus, O., Maidment, S. C. R., and Christiansen, N. A., 2009. A new long-necked ‘sauropod-mimic’ stegosaur and the evolution of the plated dinosaurs. Proceedings of the Royal Society B Published online. doi:10.1098/rspb.2008.1909.
• Further Reading:
  • Chinleana: New Long Necked Stegosaur Miragaia longicollum
  • Dinosaur Tracking: Miragaia, the Long-Necked Stegosaur
  • Discovery News: Long-Necked Stegosaur Defies Reputation
  • Dracovenator: Stegopod!
  • Everything Dinosaur: New Long-Necked Stegosaurs Discovered
  • Palaeoblog: Miragaia: The long necked stegosaur
  • SV-POW!: SV-POW! showdown: stegosaurs vs. sauropods
  • When Pigs Fly Returns: Another stegosauropod

• New Dinosaur: Epidexipteryx hui
• Name Means: Yaoming Hu’s Display Feather
• Relations: Scansoripterygid Avialaean
• Holotype: IVPP V15471, skeleton preserved with feather impressions.
• Location: Inner Mongolia, northern China
• Age: ?Middle to Late Jurassic, somewhere between 152,000,000 to 168,000,000 years ago
• Info: The well-preserved skeleton of little Epidexipteryx shows that this pigeon-sized dinosaur was covered in a fluffy feather coat, although it did not possess any contour feathers that would have enabled it to fly. It did, however sport two pairs of long ribbon-like plumes that fanned out from the tip of its rather short tail, presumably used for some sort of display. Other interesting features include its enlarged, forward-curving front teeth and its unusually proportioned hip bones. Its describers suggest that Epidexipteryx was related to the long-fingered Epidendrosaurus, and that these unusual little dinosaurs are examples of a previously unknown diversity of theropods near the origin of birds.
• Reference: F. Zhang, Z. Zhou, X. Xu, X. Wang and C. Sullivan, 2008. A bizarre Jurassic maniraptoran from China with elongate ribbon-like feathers Nature 455: 1105-1108.
• Elsewhere on the Web:
  • Nature: Figures and Tables
  • Palaeoblog: Epidexipteryx, Jurassic Feathered Dinosaur
  • Catalog of Organisms: A New Stem-Bird and Publication in the Digital Age
  • BBC News: New Feathered Dinosaur Discovered
  • Dave Hone’s Archosaur Musings has a guest post by one of the describers of Epidexipteryx, Corwin Sullivan: The Vampire Peacock of Daohugou

New Dinosaur: Glacialsaurus hammeri
Name means: Hammer’s Frozen lizard

Relations: Basal sauropodomorph (prosauropod) dinosaur
Location: Beardmore Glacier region, Antarctica
Age: Early Jurassic, 190,000,000 years ago

Material: Partial right foot and ankle, partial left femur
Est. Length: 8 meters (25 ft) long
Est. Weight: 5 tons

Glacialsaurus hammeri is only the second dinosaur described from the Jurassic of Antarctica, the first being the pompadour-crested theropod Cryolophosaurus ellioti. Although fragmentary, the remains of Glacialsaurus identify it as a prosauropod, one of several types of early long-necked dinosaurs that split off from the sauropodomorph line before true sauropods like Apatosaurus and Camarasaurus evolved. Other fossils found in the same rock formation as Glacialsaurus may come from a true sauropod, suggesting that prosauropods survived alongside their more advanced relatives for a time in the Early Jurassic.

Technical article: Smith, N. D. and Pol, D. 2007. Anatomy of a basal sauropodomorph dinosaur from the Early Jurassic Hanson Formation of Antarctica. Acta Palaeontologica Polonica 52 (4): 657–674. PDF.

Elsewhere on the web:

• Laelaps
• Palaeoblog
• The Dragon’s Tales
• Wired News
• Eurekalert

Further Reading:

Charbonnier, S., Vannier, J., and Riou, B. New sea spiders from the Jurassic La Voulte-sur-Rhône Lagerstätte. Proceedings of the Royal Society B. Published online. doi:10.1098/rspb.2007.0848

A hi-res image of three of the fossils is available here.

National Geographic News has the story, as does Afarensis.

In 1979, two hikers came across several enormous vertebrae weathering out of Jurassic-aged mudstones near the top of a mesa northwest of Albuquerque, New Mexico. They reported their find, which was on federal land, to the local office of the Bureau of Land Management. BLM paleontologists identified the bones as coming from a large sauropod dinosaur, but lacked the resources to begin a proper excavation of the site. The bones were buried to protect them from further erosion (or unauthorized excavation) until 1985, when the New Mexico Museum of Natural History was about to open in Albuquerque.

A friend of one of the fossil’s disoverers reported the find to Dr. David Gillette, then Curator of Paleontology at the fledgling NMMNH. After a trip to the site, Gillette began making the necessary arrangments to excavate the bones that had been discovered and, eventually, a much greater amount of fossil material that was buried within the mesa. Over the next decade, several tons of rock and bone were chipped from the site and transported to the NMMNH. There, staff and volunteer preparators began the arduous process of separating the fossils from the surrounding rock (matrix)—a process complicated by the fact that both fossil and matrix were similar in color, hardness, and in some areas, texture.

After some of the first bones (vertebrae from the middle of the tail) were prepared, Gillette began comparing them to their counterparts in other sauropods. Although they were closest in form to the well-known Diplodocus, they were much larger and differed in their overall proportions. Gillette concluded that they were unique enough to warrant their own genus, and in 1991 he published an article naming the fossil Seismosaurus halli, or “Hall’s Earth-shaking Lizard.” (Because the name was intended to honor both Reverend James Hall and his wife, Ruth, for their contributions to New Mexico paleontology, it was later emended to the plural possessive form Seismosaurus hallorum.) In his description, Gillette estimated that, when alive, Seismosaurus might have been up to 52 meters (170 feet) long.

By the closing years of the 20th century, enough of the fossils had been prepared to begin the creation of an accurate skeletal reconstruction of Seismosaurus. As new teams of researchers began to compare Seismosaurus to Diplodocus, they began to suspect that some of the bones that Gillette had placed towards the middle of the tail had, in fact, been located much closer to the hips. This realization significantly shortened the animal’s overall length, from a near-record 170-foot maximum down to a “mere” 110 feet long.

More importantly, this revised interpretation eliminated several of the anatomical characters that Dr. Gillette had used to distinguish Seismosaurus from Diplodocus. Most of the characters that remained had to do with relative proportions of the vertebrae, and several researchers suggested that these were well within the range of variation one might expect in a dinosaur genus like Diplodocus.

Lucas et al. 2006 Figure 2: A diagram I worked up showing the differing interpretations
of bone location in the Seismosaurus holotype.

By 2004, when a reconstructed skeleton was put on display in the New Mexico Museum of Natural History and Science (the institution’s name has lengthened with age), only one feature remained that was clearly unique to Seismosaurus—an unusual prong at the tip of its ischium (the backward-pointing bone in its hip). But when this bone was prepared more thoroughly, it became apparent that the ‘prong’ was actually a piece from one of the vertebrae that had broken off post-mortem and drifted beneath the animal, coming to rest at the tip of the ischium. Eventually the two bones were cemented together by the nearly indistinguishable matrix.

A new paper in the NMMNHS Bulletin discusses the features unique to Seismosaurus, shows the before-and-after ischium, and, with this last notable character gone, sinks the earth-shaking Seismosaurus into the long-established genus Diplodocus. It is kept as a separate, over-sized species—Diplodocus hallorum—based on its relative proportions and the paddle-like shape of some of the chevron bones in its tail. However, the authors note that the other four named species of Diplodocus are in need of re-examination, and there is no guarantee that the dinosaur formerly known as Seismosaurus would retain even a specific level of distinction in the light of current taxonomic thought.

Further Reading:

Gillette, D. D. 1991. Seismosaurus halli, gen. et sp. nov., a new sauropod dinosaur from the Morrison Formation (Upper Jurassic/Lower Cretaceous) of New Mexico, USA. Journal of Vertebrate Paleontology, v. 11, pp. 417–433.

Gillette, D. D. 1994. Seismosaurus: The Earth Shaker. New York, Columbia University Press. HTML.

Herne, M. C. and Lucas, S. G. 2006. Seismosaurus hallorum: Osteological reconstruction from the holotype. New Mexico Museum of Natural History and Science Bulletin 36. pp. 139–148.

Lucas, S. G., Spielmann, J. A., Rinehart, L. F., Heckert, A. B., Herne, M. C., Hunt, A. P., Foster, J. R., and Sullivan, R. M. 2006. Taxonomic status of Seismosaurus hallorum, a Late Jurassic sauropod dinosaur from New Mexico. New Mexico Museum of Natural History and Science Bulletin 36. pp. 149–161.

This paper has inspired a couple of very good posts on Darren Naish’s Tetrapod Zoology blog, and I’ll refer the reader here and here for his excellent summary of the history and validity of A. fragillimus. I’ll focus on the new size estimates, and why A. fragillimus was even larger than I had imagined.

My initial estimate of the size of A. fragillimus was made by comparing Cope’s reconstruction of the type vertebra to the vertebrae of local giant Seismosaurus hallorum (properly Diplodocus hallorum at this point, but more on that later). Scaling up a Seismosaurus to fit Cope’s estimate of a 6 to 7 foot tall A. fragillimus vertebrae results in an animal about 50 meters (160 feet) long.

As it turns out, Cope may have significantly underestimated the height of the vertebra of A. fragillimus. Carpenter compared Cope’s drawing of the Amphicoelias fragillimus specimen with material known from another, more reasonably-sized species of Amphicoelias, A. altus. Scaling an A. altus dorsal to fit the A. fragillimus material results in a whopping 2.7 meter (8.8 foot) tall bone!

From left to right:

• The diplodocid Seismosaurus hallorum dorsal 8 (after Herne and Lucas 2006),
• The diplodocid Amphicoelias fragillimus dorsal 9/10? as reconstructed by Cope 1878,
• The diplodocid Amphicoelias fragillimus dorsal 9/10? as reconstructed by Carpenter 2006, scaled from
• The diplodocid Amphicoelias altus dorsal 10? (after Carpenter 2006, modified from Osborn and Mook 1921),
• The titanosaur Puertasaurus reuili dorsal 2 after Novas et al 2005, Figure 2). Scale bar equals 1 meter.

Carpenter scaled up a Diplodocus to fit this new super-sized vertebra, and his Amphicoelias fragillimus measures a full 58 meters (190 feet) from snout to tail. The estimated mass of this mega-sauropod would be about 122,400 kg (about 270,00 lbs or 135 tons).

Here is the size comparison I made last summer, comparing the big diplodocids Seismosaurus hallorum (33 meters) and Amphicoelias fragillimus (my 50-meter estimate) to some of the largest titanosaurs, Argentinosaurus huinculensis (at 37.5 meters, the length of the skeletal reconstruction on display at the Fernbank Museum) and Puertasaurus reuili (at 40 meters, the upper estimate reported in the media). Click on the image for a larger version:

In Figure 3 of his paper, Carpenter shows a more detailed size comparison of mega- and super-sauropods (mega-sauropods are defined as those that reach or exceed 30 meters in length)—a copy of it is posted here. In addition to an enormous Amphicoelias, it shows Seismosaurus (C) and a silhouette of Argentinosaurus (F) based on the profile of the related titanosaur Saltasaurus. This new titanosaur shape changes their dimensions considerably, shrinking Argentinosaurus from 37.5 down to 30 meters in length.

Based on this information, I resized and revised and came up with the following size comparison (click for a larger version):

From left to right:

• The diplodocid Seismosaurus hallorum (skeleton on display at the NMMNHS–33 m. (110 ft.) long),
• The diplodocid Amphicoelias fragillimus (est 58 m. (190 ft.) long),
• Homo sapiens (1.8 m. (6 ft.) tall),
• African Elephant Loxodonta africana (4 m. (13 ft.) tall at the shoulder),
• The titanosaur Argentinosaurus huinculensis (est 30 m. (98 ft.) long),
• The titanosaur Puertasaurus reuili (shortest reported estimate 35 m. (115 ft.) long).

Note that, in this latest estimate, Seismosaurus completely fits under the tail of Amphicoelias fragillimus!

Further Reading:

Carpenter, K. 2006. Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus Cope, 1878. New Mexico Museum of Natural History and Science Bulletin 36: pp. 131–137. PDF.

Cope, E. D. 1878. A new species of Amphicoelias. American Naturalist 12(8): pp. 563–564. JPG. HTML.

Herne, M. C. and Lucas, S. G. 2006. Seismosaurus hallorum: osteological reconstruction from the holotype. New Mexico Museum of Natural History and Science Bulletin 36: pp. 139–148.

Novas, F. E., Salgado, L., Calvo, J., and Agnolin, F. 2005. Giant titanosaur (Dinosauria, Sauropoda) from the Late Cretaceous of Patagonia. Rev. Mus. Argentino Cienc. Nat., 7(1): pp. 37–41. PDF.

Don’t forget the two posts at Tetrapod Zoology, and Matt Wedel (a.k.a. Doctor Vector) promises to weigh in on the topic, so you know that’s worth keeping an eye out for.

Volaticotherium, however, hails from well before any of these aerial upstarts. The oldest known gliding rodent is not a squirrel but an eomyid from the Late Oligocene (~25,000,000 years ago), and the earliest known evidence for flight in bats comes from the Eocene, 51,000,000 years ago. Volaticotherium is at least 70,000,000 years older than that, and could be even older. (The age of the Daohugou beds is controversial, but lies somewhere between the Early Cretaceous (~125,000,000 years ago) and the Middle Jurassic (~170,000,000 years ago).) If the older age is correct, this would mean that Volaticotherium was experimenting with aerial locomotion before the 150,000,000-year-old Archaeopteryx, the earliest known bird.

Further reading:

Meng, J., Hu, Y., Wang, Y., Wang, X., and Li, C. 2006. A Mesozoic gliding mammal from northeastern China. Nature 444, 889–893. Editor’s summary.

A larger image of the cover art by Chuang Zhao and Lida Xing is shown at National Geographic News.

12/19 Update: Much more information on Volaticotherium (and how its discovery fits into the grand arc of Mesozoic Mammal Studies) in this article by Trevor Dykes.

Apologies to all museum visitors for passing on less-than-accurate info—rest assured I’ll be cross-checking future figures before posting them.

Amphicoelias fragillimus (“Doubly hollow and very fragile”) was only known from part of a dorsal vertebra collected near Cañon City, Colorado. Cope reported that the preserved portion of the bone measured 1.5 meters in height, and estimated that the complete vertebra would have been at least 6 feet tall. (The original description is relatively short, and well out of copyright, so I’ve taken the liberty of transcribing it into the HMNH Library. A scan of the description as it appeared in the journal American Naturalist is available elsewhere.)

Unfortunately, today nobody knows where this fossil is. How, you might ask, could anyone lose the better part of a six-foot-tall vertebra? Definitive answers are lacking, but most suspect that it crumbled to pieces in storage or transit (Cope didn’t call it “fragillimus” for nothing). So all we are left with is Cope’s original description and figure (reproduced to the left), making A. fragillimus something of a dinosaurian fish-story—the big one that got away.

Provided that Cope’s description is accurate (a claim not everyone is willing to accept, given the rather colorful state of paleontology at the time), Ampicoelias fragillimus would have been by far the largest diplodocid sauropod ever described. Diplodocids were a family of lean, long and low sauropods, whose members include Apatosaurus (75 feet long), Diplodocus (83 feet long), Barosaurus (93 feet long), and Seismosaurus (110 feet long). Scaling up a Seismosaurus skeleton to make the vertebrae as large as Amphicoelias fragillimus results in an animal about 160 feet long!

How does this compare to the newly-described Puertasaurus reuili? Puertasaurus is estimated to be 115 to 130 feet long, so it couldn’t match the estimated length of Amphicoelias. But Puertasaurus was a titanosaur, a group that had a wider, heavier, and stockier build than their distant diplodocid cousins. So, even though it would have taken more steps to walk the length of Amphicoelias fragillimus, Puertasaurus would still have been a much somewhat more massive animal. This is easy to see when you compare their vertebrae side-by-side: See the revision below:

From left to right:

• The diplodocid Seismosaurus hallorum dorsal 3 (from the Jurassic exhibit at the NMMNHS),
• The diplodocid Amphicoelias fragillimus dorsal 9/10? (after Cope 1878),
• The titanosaur Argentinosaurus huinculensis dorsal 4? (after Novas et al 2005),
• The titanosaur Puertasaurus reuili dorsal 2 (ibid). Scale equals 1 meter.

To see the scale of the different animals, I worked up a rough series of silhouettes. Click on the image for a larger version:

From left to right:

• The diplodocid Seismosaurus hallorum (skeleton on display at the NMMNHS–110 ft. long),
• The diplodocid Amphicoelias fragillimus (est. 160 ft. long),
• Homo sapiens (6 ft. tall),
• The titanosaur Argentinosaurus huinculensis (skeleton on display at the Fernbank Museum–123 ft. long),
• The titanosaur Puertasaurus reuili (est. 135 ft. long),
• African Elephant Loxodonta africana (13 ft. tall at the shoulder).

Note that this image is no more than a rough guideline—none of the sauropods are known from more than a 30% complete skeleton, and the proportions of the titanosaurs are particularly sketchy. But I think it is safe to say that the enormous sauropods coming out of South America are giving even the most legendary giants of the western U.S. a run for their money.

Revision 8/18: Something isn’t quite right about the images above.
Something seemed amiss when I saw this image over at NewCritters.com. The Puertasaurus vertebra pictured there couldn’t be as large as I’d made it in the comparison above.

After double-checking the figures in Novas et al.’s paper, I realized that they had illustrated this vertebrae with two different scales. In Figure 2 of the paper, the scale shows it to be consistent with the reported height of 106 centimeters. In Figure 3, where this vertebra is compared to those of other sauropods, the scale shows it to be at least 25% larger. Since the latter figure had an Argentinosaurus vertebra to (what I assumed was) the same scale, I used that figure for the above diagram without double-checking the text. A revised vertebral comparison (showing the discrepancies in the original figures) is shown below:

From left to right:

• The diplodocid Seismosaurus hallorum dorsal 3 (from the Jurassic exhibit at the NMMNHS),
• The diplodocid Amphicoelias fragillimus dorsal 9/10? (after Cope 1878),
• The titanosaur Puertasaurus reuili dorsal 2 (after Novas et al 2005, Figure 3),
• The titanosaur Puertasaurus reuili dorsal 2 (after Novas et al 2005, Figure 2). Scale equals 1 meter.

What a difference in size! The smaller version on the right is consistent with the reported measurements and photographs, and I feel fairly confident that this is the correct size. It makes it much smaller, however, and much closer in scale to Seismosaurus than Amphicoelias.

How would this affect the size of the animal? More on that later…

Revision 8/19: Updating the animals

In putting together the silhouette comparison above, I modified an outline of Gabriel Lio’s Puertasaurus restoration for the two titanosaurs. The resulting outlines of Argentinosaurus and Puertasaurus seemed a little beefy to me, but since they were in keeping with the relative sizes of the vertebrae, I figured they were fairly close. With the revised size of the Puertasaurus vertebra, I thought I’d try another method.

A Google image search revealed a couple of good photos of the skeletal reconstruction of Argentinosaurus huinculensis mounted at the Fernbank Museum of Natural History, which comes in at 123 feet long. Using these images, I came up with a revised giant-titanosaur silhouette for Argentinosaurus and Puertasaurus which is considerably more svelte. However, plugging them into the comparison with Seismosaurus and Amphicoelias shows that they were still nothing to sneeze at (click on the image for a larger version):

From left to right:

• The diplodocid Seismosaurus hallorum (skeleton on display at the NMMNHS–110 ft. long),
• The diplodocid Amphicoelias fragillimus (est. 160 ft. long),
• Homo sapiens (6 ft. tall),
• African Elephant Loxodonta africana (13 ft. tall at the shoulder).
• The titanosaur Argentinosaurus huinculensis (skeleton on display at the Fernbank Museum–123 ft. long),
• The titanosaur Puertasaurus reuili (maximum est. 135 ft. long).

• Afarensis goes into more detail on the bone histology that allowed researchers to determine that the six-meter sauropod was fully grown.
• A German press release from the University of Bonn contains many more images (scroll down). An imageless English translation of the press release is available here.
• GrrlScientist has the story over at Living the Scientific Life.
• And Octavio Mateus, one of the authors that described Europasaurus, has made the full article available for download from the comprehensive DinoData.net: Direct PDF link.

Happy reading!