Sunday, October 14, 2018

Compact Thescelosaurus Year Three

It's mid-October, with National Fossil Day coming up (Wednesday the 17th) and the anniversary of the original Thescelosaurus just behind us (Sunday the 7th). It's also time for something new for The Compact Thescelosaurus on its third birthday. Last year, pterosaurs joined dinosaurs and choristoderes. This year, plesiosaurs and a variety of more basal sauropterygians and possible sauropterygians join them.

Elasmosaurid Thalassomedon haningtoni, Denver Museum of Nature and Science

Sunday, October 7, 2018

Hyoliths III: Season of the Hyolith

You may remember that last year we had some Paleozoic excitement with the publication of specimens showing the enigmatic hyoliths to be lophophorates, related to brachiopods, bryozoans, and phoronid worms (Moysiuk et al. 2017). Independent support for this position has just been published based on Chinese Cambrian specimens. In this case, hyoliths are not only lophophores, but they are stem brachiopods (closely related to modern brachiopods, but not within the group including modern brachiopods, the crown brachiopods), based on the presence of pedicles in a species of basal hyolith (Sun et al. 2018a).

The pedicle is a fleshy organ, found in most brachiopods, which anchors the shell to the substrate. (Curiously enough, our last visit with the brachiopods covered the strophomenids, noted for not having pedicles.) Sun et al. (2018a) describe a new hyolith taxon, Pedunculotheca diania, which has the typical elongate pointed main shell and lid-like operculum of hyoliths (a bit more oval in cross-section than the classic triangles we've seen so far), with the addition of a short nonmineralized stalk ending in a small holdfast growing from the tip of the shell.

An anchored hyolith, like Pedunculotheca diania, would be a suspension feeder, but other, more derived hyoliths were unattached (Sun et al. 2018a). Moysiuk et al. (2017) interpreted hyoliths in general as filter feeders, but it appears that hyoliths were more ecologically flexible. Recent publications have documented aggregations of hyoliths around coprolites (Kimmig and Pratt 2018; Sun et al. 2018b) and dead animals (Sun et al. 2018b), indicating scavenging/detritivore roles. Because skeletal fragments have never been reported in hyolith guts, Sun et al. (2018b) suggested that they focused on the more fluid phase of the decomposing detritus (or at least the non-mineralized phase), or on microbial films growing around the detritus. The authors also found hyoliths associated with small burrows, indicating that they could enter the uppermost substrate.

In my quest to always have different hyolith images when the topic comes up, here is Figure 2a from Plate LXIII in Walcott (1899). It is a "reproduction of photograph of a slab of sandstone, with numerous specimens of H. primordialis, from the St. Croix sandstone of Wisconsin. The small shells are identical with H. gregaria of M. and H. [Meek and Hayden]." The publication is actually on fossils of Yellowstone National Park, but Walcott had identified hyoliths there as basically the same as H. primordialis from Wisconsin, which is why he included this figure. Later, the Yellowstone hyoliths would be transferred to a new species (H. gallatinensis Resser 1938) and eventually genus (Haydenoconus Malinky 2014).

References

Kimmig, J, and B. R. Pratt. 2018. Coprolites in the Ravens Throat River Lagerst├Ątte of northwestern Canada: implications for the Middle Cambrian food web. Palaios 33:125–140. doi:10.2110/palo.2017.038.

Malinky, J. M. 2014. Cambrian Hyolitha and problematica from West Laurentian North America: taxonomy and palaeobiology. Alcheringa 38(3):338–362.

Moysiuk, J., M. R. Smith, and J.-B. Caron. 2017. Hyoliths are Palaeozoic lophophorates. Nature 541:394–397. doi:10.1038/nature20804.

Resser, C. E. 1938. Fourth contribution to nomenclature of Cambrian fossils. Smithsonian Miscellaneous Collections 97(10).

Sun, H., M. R. Smith, H. Zeng, F. Zhao, G. Li, and M. Zhu. 2018a. Hyoliths with pedicles illuminate the origin of the brachiopod body plan. Proceedings of the Royal Society B: Biological Sciences 285(1887). doi:10.1098/rspb.2018.1780.

Sun, H.-J., F.-C. Zhao, R.-Q. Wen, H. Zeng, and J. Peng. 2018b. Feeding strategy and locomotion of Cambrian hyolithides. Palaeoworld 27(3):334–342. doi:10.1016/j.palwor.2018.03.003.

Walcott, C. D. 1899. Cambrian fossils. Pages 440-478 in Geology of the Yellowstone national park. U.S. Geological Survey, Washington, D.C. Monograph 32.

Sunday, September 30, 2018

Ledumahadi mafube

For reasons which are mysterious to me, this blog has become full of sauropodomorphs of one kind or another. It's been a good year for them. The latest is Ledumahadi mafube from the Elliot Formation of South Africa, an early giant near the base of the sauropod tree.

Sunday, September 23, 2018

Your Friends The Titanosaurs, part 4: Antarctosaurus miscellany

In this installment, we take care of some housekeeping before moving on. We've limited true Antarctosaurus to A. wichmannianus, leaving us with a few extra species which haven't amounted to all that much. (A. septentrionalis is excluded from that comment, now having its own genus Jainosaurus.) "A." brasiliensis and "A." jaxarticus might not be the most exiting species, but we've also got the hidden giant "A." giganteus.

Sunday, September 16, 2018

Fates of collections

Despite our best intentions and planning, a lot of things can happen to a collection. We saw an extreme example of this recently in the devastating fire at the National Museum of Brazil on September 2. Many fossil collections have been partially or completely lost to fires since people began accumulating specimens for scientific purposes, and we can be sure that there will be losses to come from fires. Of course, fires are not the only way institutions have lost collections. Apart from occasional attrition (specimens becoming misplaced, damaged or destroyed through accidents, lost while on loans, or outright stolen), large portions of paleontological collections to entire collections have gone from their original institutions in a variety of ways.

Fire

Although fossils are, generally, basically rocks, fire can indeed cause damage to rocks. Water used in firefighting can also damage rocks, for example rocks composed of shrink-swell clays, and rocks with significant organics are vulnerable to both fire and water damage. (And if the specimens are late Quaternary paleoecological materials such as dung or middens? You've got a repeat of Rampart Cave in the museum.) Rocks can also be damaged by heavy objects falling on them during fires. Other issues may include, but are not limited to, being covered by melted materials and being subjected to explosive events. Furthermore, even if a given fossil survives a fire, it may be lost during recovery efforts.

Fires are not as common as they once were, thanks to improvements in fireproofing and fire suppression, although these advances cannot help if they are not implemented or are otherwise unavailable. For example, the National Museum of Brazil lacked sprinkler systems, and water for firefighting had to be brought to the scene. A significant cause of many late 19th century and early 20th century fires was early electrical systems.

Here are a few U.S. fires I've come across that affected fossil collections; it is certainly not exhaustive! It does cover nine decades and everything from two state capitols to a modest facility in the Big Bend of Texas:
  • Academy of Science of St. Louis, May 1869: included some of Benjamin Franklin Shumard's collections;
  • Minnesota State Capitol, St. Paul, March 1, 1881: this fire claimed the Minnesota Academy of Science collections, which among other things held mammoth or mastodon fossils from Stillwater;
  • Texas State Capitol, Austin, November 9, 1881: this fire destroyed the remnants of Shumard's Texas Geological Survey specimens;
  • Science Hall, University of Wisconsin–Madison, December 1, 1884: this building housed the Wisconsin State Collection, including some of R. P. Whitfield's St. Croix fossils;
  • Academic Hall, University of Missouri, Columbia, January 9, 1892: another group of Shumard's fossils was lost in this blaze;
  • Williston Hall, Mount Holyoke College, South Hadley, December 22, 1917: in dinosaur paleontology, this fire is best known for the loss of the holotype of Podokesaurus holyokensis;
  • Chisos Basin Civilian Conservation Corps barracks, December 24, 1941: this building housed a small museum of Big Bend fossils;
  • Williams Hall, Lehigh University, Bethlehem, February 1956: a fire in the third floor of this building is implicated in the disappearance of a collection of Ordovician fossils collected near Delaware Water Gap.

War

Many collections have been partially or wholly destroyed in wars, particularly at European institutions during the two World Wars. The poster child for these losses is the holotype of Spinosaurus aegyptiacus, lost along with other Egyptian fossils (including Aegyptosaurus baharijensis) when the Paleontological Museum in Munich was hit by bombs during a night raid, April 24–25, 1944. Specimens and larger collections have sometimes also been looted, for commercial value or as a kind of "scientific imperialism". Wars and other armed conflicts have not been a major issue for collections in the U.S. since the Civil War, when there were few significant collections. One exception was the Texas Geological Survey collection, left in limbo at the start of the Civil War. Almost all of the specimens amassed by Benjamin Franklin Shumard for the survey were lost during the war when the State Capitol was turned over to the manufacturing of percussion caps. (In case you're wondering, that makes three fires and one loss-by-neglect for Shumard, who simply could not catch a break.)

Disbursement or transfer

While you may be under the impression that your favorite museum accumulated all of its specimens on its own, maybe with some scattered donations thrown in, if you scratch the surface you will probably find that the museum has absorbed multiple substantial collections over the years. These may be personal collections (such as the collections of Edward Drinker Cope and James Hall at the American Museum of Natural History), corporate collections (think invertebrates and microfossils collected for oil companies), or collections from other institutions (for example, in recent decades the Natural History Museum of Los Angeles County has incorporated collections from UCLA, Cal Tech, CSUN, and USC). The fact is that many places have accumulated collections over the years, only to end up sending them elsewhere for various reasons: change in direction, loss of funding, streamlining of collections, retirement of key staff, lack of interest, etc. This kind of movement can involve entire collections or only parts of collections (paleobotany seems peculiarly vulnerable to this). Technically speaking, the specimens are not "lost", although relocation of a collection can result in loss or damage to specimens, and the collections can sometimes *seem* lost if you're trying to track them down years after the fact!

Although small institutions are probably most likely to send their collections elsewhere, even storied, historically significant collections have been transferred. Princeton gave their vertebrate paleontology collections to Yale in 1985 when the university decided to cut the paleontology program. The USGS collections in Washington and Menlo Park went to the Smithsonian and the University of California Museum of Paleontology, respectively, following political wrangling in the mid-1990s. Integrating established collections into their new homes can be a headache, and specimens from large added collections often retain some part of their original identity. For example, fossils from Princeton in the Yale collections include "PU" in their catalog identification.

Sunday, September 9, 2018

Yizhousaurus sunae

I originally had something else in mind for today, but it was heavily photo-dependent, and the photos weren't coming out very well (unresolved lighting and depth-of-field issues). I will have to try again some other time. Meanwhile, here comes Yizhousaurus sunae to the rescue! I'm not quite sure why "prosauropods" should have featured so frequently here (see also Bagualosaurus, Meroktenos, Xingxiulong, and two visits with Anchisaurus), but there you go.

Figure 3 from Zhang et al. (2018) (check the link for the lengthy caption). Note that the quadrate and associated bones are displaced from the back of the skull, which obscures the complete shape of the profile.

Sunday, August 26, 2018

Dryosaurus elderae and the revenge of Nanosaurus agilis

It's been a busy few days over at The Compact Thescelosaurus, with new alvarezsaurs, nodosaurs, and dryosaurs. For this post, I'm going to focus on Carpenter and Galton (2018), which not only describes new species Dryosaurus elderae, but also is quite important for previous subject Nanosaurus agilis, and in general ticks off several of my boxes anyway ("hypsilophodonts", Morrison Formation, National Park Service areas, etc.).

Figure 2 from Carpenter and Galton (2018), showing the distribution of bipedal Morrison ornithischians. A keen-eyed observer who's familiar with the Morrison fauna might notice the absence of Drinker nisti and Othnielosaurus consors, and an abundance of Nanosaurus agilis...