Issi saaneq and Brighstoneus simmondsi

A couple of new non-theropod names have come down the pipe since the beginning of November, and I thought I'd cover them together. Let's tackle the earlier of the two (both geochronologically and publication-wise) first.

Issi saaneq

We haven't had a new basal sauropodomorph around here in a while, not since Kholumolumo ellenbergerorum in April 2020. Here's one that marks the first non-avian dinosaur named from Greenland: Issi saaneq. You might recall having seen records of Plateosaurus from Greenland (e.g., Jenkins et al. 1994); I. saaneq is the new home for that material.

Genus and Species: Issi saaneq, derived from two Kalaallisut words. "Issi" means "cold" and "saaneq" means "bone", giving us an apt description of the discovery conditions (Beccari et al. 2021).

Citation: Beccari, V., O. Mateus, O. Wings, J. Milàn, and L. B. Clemmensen. 2021. Issi saaneq gen. et sp. nov.—A new sauropodomorph dinosaur from the Late Triassic (Norian) of Jameson Land, central east Greenland. Diversity 13(11):561. doi:10.3390/d13110561.

Stratigraphy and Geography: The two described specimens of I. saaneq were found at the "Iron Cake" site at Macknight Bjerg, Jameson Land, central east Greenland. The fossils came from the upper Malmros Klint Formation of the Fleming Fjord Group, dated to the middle Norian of the Late Triassic, perhaps 214 million years ago. The Malmros Klint Formation is interpreted as a shallow lacustrine or playa lake setting. A characteristic Late Triassic fauna of cartilaginous and bony fishes, lungfish, temnospondyl amphibians, turtles, aetosaurs, phytosaurs, pterosaurs, theropods, sauropodomorphs, and mammal cousins has been found in the Malmros Klint Formation and overlying Ørsted Dal Formation (Beccari et al. 2021). (In older references, both formations were ranked as members of the Fleming Fjord Formation.)

Holotype: NHMD 164741 (GeoCenter Møns Klint, Møns Klint, Denmark), a partial skull at least 24.37 cm long (9.594 in) belonging to a late juvenile or young subadult individual. It was collected in 1991. Most of the right side and the tips of the jaws are missing (Beccari et al. 2021). It is partially articulated but also somewhat smooshed and so forth.

The holotype of Issi saaneq, Figure 4 in Beccari et al. (2021) (which see for explanation, although you can figure out a lot of them from here). Scale bar is 50 mm (2.0 in). CC BY 4.0.

A second specimen, NHMD 164758 collected in 1995, is designated the paratype. This is a nearly complete skull of a somewhat younger juvenile, missing the braincase region. Undescribed postcranial material may also belong to it (Beccari et al. 2021). Additionally, the authors mentioned two other sauropodomorph specimens collected from the site in 2012, NHMD 164734 and 164775, but again these are undescribed.

This one (Figure 37 from Beccari et al. 2021) might be a little easier to interpret. A is the holotype and B is the paratype. Scale bar is 50 mm (2.0 in). CC BY 4.0.

It's not too hard to see why the holotype was originally referred to Plateosaurus. It's got the classic "middling prosauropod" look, generally elongate and rectangular, reconstructed with a somewhat droopy tip of the snout. Completely unsurprisingly, I. saaneq clades with plateosaur-grade sauropodomorphs (Plateosauridae, Plateosauridae plus Unaysauridae, or whatever you might prefer) (Beccari et al. 2021). The differences from others of this grade are subtle, and with I. saaneq being found as the sister taxon to Plateosaurus, there is a potential argument that the differences could be at the species level rather than the genus level. That comes down to the sensitivity of your genericometer, though.

Brighstoneus simmondsi

After a few years of stability, the cloud of genera and species formerly included in Iguanodon gains another member. 

Genus and Species: "Brighstoneus" refer to the village of Brighstone on the Isle of Wight. Lockwood et al. (2021) specify this is a double reference because Brighstone is near the discovery site and was home to the Reverend William Fox (of Hypsilophodon foxii and Polacanthus foxii fame). The species name honors Keith Simmonds, who found the specimen (Lockwood et al. 2021). (You don't know how many times I've had to correct myself or consciously keep from slipping a "t" to make "Brightstoneus", and it was only published on Thursday.)

Citation: Lockwood, J. A. F., D. M. Martill, and S. C. R. Maidment. 2021. A new hadrosauriform dinosaur from the Wessex Formation, Wealden Group (Early Cretaceous), of the Isle of Wight, southern England. Journal of Systematic Palaeontology (advance online publication). doi:10.1080/14772019.2021.1978005.

Stratigraphy and Geography: The type and only known specimen was found west of Grange Chine on the south coast of the Isle of Wight, in the Wessex Formation. It was discovered in 1978 at the same site as the type specimen of Neovenator salerii (Lockwood et al. 2021). Normally I would make a crack about how of course the theropod was described first, but in this case the ornithopod was first thought to be another specimen of Iguanodon.

Holotype: MIWG 6344 (MIWG.6344 in some reports) (Isle of Wight County Museum Service, under the older "Museum of Isle of Wight Geology" accession), a partial skeleton including a partial skull (missing essentially the parts from the eyes back), eight presacral vertebrae, the sacrum, six caudals, 14 ribs, both ilia, the right ischium, what might be a prepubic process, and the right femur. A few other bones belonging to the individual are held privately and were not described (Lockwood et al. 2021).

The specimen MIWG 6344 has appeared occasionally in the literature for a couple of decades. Several bones were illustrated as examples of "Iguanodon atherfieldensis" (=Mantellisaurus) in Naish and Martill (2001), for example. A few years later Greg Paul considered it referable to Dollodon sp. (the genus he coined for the gracile Bernissart iguanodont) (Paul 2008). McDonald (2012) put both MIWG 6344 and Dollodon in Mantellisaurus. None of these publications give much detail about MIWG 6344, aside from noting the long, slender dentary. Lockwood et al. (2021) therefore is the first to show it off. The immediate impression is of an animal with a very long muzzle indeed, with an unexpected nasal arch formed entirely by the nasal bones. As is appropriate for the long jaw, there are more teeth than in other "iguanodontid"-grade iguanodonts, with 28 per lower jaw (Lockwood et al. 2021).

Cue the "long face" jokes. Figure 10 of Lockwood et al. (2021), comparing the skulls of Brighstoneus (A) and Mantellisaurus (B). Scale bar is 100 mm (3.94 in). CC BY-NC-ND 4.0.

Another feature, one which hasn't been pointed out as widely, is the tall neural spines. Tall neural spines are not unprecedented among "iguanodontid"-grade iguanodonts (Ouranosaurus having one of the most famous sails among dinosaurs), and B. simmondsi is certainly not in that league, but it did have notably tall spines on the dorsals, sacrals, and anterior caudals. Almost all of the measurable neural spines are at least three times the heights of their centra. The most anterior of the preserved caudals rocks a spine 3.9 longer than the centrum height, which not only handily beats the contemporary Iguanodon and Mantellisaurus, but also exceeds Ouranosaurus (3.4) (Lockwood et al. 2021). The spine doesn't look quite as tall, though, because there's more posterior slant on B. simmondsi.

And this is where the grim specter of taxonomic second-guessing creeps in. In some ways, B. simmondsi is kind of an inadvertent backdoor Dollodon. McDonald (2012) wrote that the cranial and postcranial bones of MIWG 6344, the type specimens of M. atherfieldensis and Dollodon bampingi, and a couple of other specimens "are virtually indistinguishable from each other", which seems a bit generous: there *are* visible differences, although they've been attributed to growth stages, variation, preservation/restoration, and so forth. The type specimen of M. atherfieldensis doesn't have a neural spine to its name, and I was under the impression it was not fully grown, but Lockwood et al. (2021) report that the type specimens of B. simmondsi, M. atherfieldensis, and D. bampingi have neurocentral fusion (neural arches fused to the centra), so perhaps the spines were eroded away? If we are to understand that the type of M. atherfieldensis would not have grown up into Brighstoneus with its long face and nasal arch, does that mean that Dollodon, with its longish face and moderately exaggerated neural spines, also deserves to be re-evaluated?

References

Beccari, V., O. Mateus, O. Wings, J. Milàn, and L. B. Clemmensen. 2021. Issi saaneq gen. et sp. nov.—A new sauropodomorph dinosaur from the Late Triassic (Norian) of Jameson Land, central east Greenland. Diversity 13(11):561. doi:10.3390/d13110561.

Jenkins, F. A., Jr., N. H. Shubin, W. W. Amaral, S. M. Gatesy, C. R. Schaff, L. B. Clemmensen, W. R. Downs, A. R. Davidson, N. Bonde, and F. Osbæck. 1994. Late Triassic continental vertebrates and depositional environments of the Fleming Fjord Formation, Jameson Land, east Greenland. Meddelelser om Grønland Geoscience 32.

Lockwood, J. A. F., D. M. Martill, and S. C. R. Maidment. 2021. A new hadrosauriform dinosaur from the Wessex Formation, Wealden Group (Early Cretaceous), of the Isle of Wight, southern England. Journal of Systematic Palaeontology (advance online publication). doi:10.1080/14772019.2021.1978005.

McDonald, A. T. 2012. The status of Dollodon and other basal iguanodonts (Dinosauria: Ornithischia) from the Lower Cretaceous of Europe. Cretaceous Research 33:1–6.

Naish, D., and D. M. Martill. 2001. Ornithopod dinosaurs. Pages 60–132 in D. M. Martill and D. Naish, editors. Dinosaurs of the Isle of Wight. The Palaeontological Association, London, United Kingdom. Field Guide to Fossils 10.

Paul, G. S. 2008. A revised taxonomy of the iguanodont dinosaur genera and species. Cretaceous Research 29:192–216.