Link to a different artistic rendering of Deinocheirus

Not only does this post at the blog Antediluvian Salad present a new and interesting artistic rendering of Deinocheirus by Andrey Atuchin, but it also delves into the ecology of the Cretaceous-era Nemegt basin to ponder the question “Was Deinocheirus the largest waterfowl of all time?”

I won’t steal any thunder but will encourage you to click through, look, and read.

 

Link to artistic rendering of Deinocheirus

Paleoartist Luis V. Rey has put together a fascinating and fantastic artistic rendering of Deinocheirus factoring in new material from the last year — neural spines, duck bill, and all.  Go check it out!

As a bonus feature, Rey’s post also features a photo of Deinocheirus‘s discoverer Halszka Osmólska pondering the dinosaur’s eponymous “terrible hands.”  Even without the Deinocheirus illustration, that photo alone would be worth clicking through for a look.

A Deinocheirus Skull!

Recall Deinocheirus, the theropod dinosaur (read: T. rex relative) best known for its eight-foot-long arms and huge, impressively clawed hands.  Last fall, paleontologists presented lots of newly discovered Deinocheirus material at the Society for Vertebrate Paleontology annual meeting.  In fact, this new material provided a nearly complete picture of Deinocheirus, with one notable exception: there was no Deinocheirus head.  I wrote about this and quoted the following from Stephen Brusatte via Brian Switek: “There are rumors of a skull being privately collected, looted from Mongolia, and sold on the black market to a legitimate museum in Europe.”  Intriguing.

Now it looks like there was some truth to the rumors: infomongolia.com has reported that a Deinocheirus skull — the first to be identified as such! — was returned just last week to the nation of Mongolia by the Royal Belgian Institute of Natural Sciences.  Excitingly, the report includes pictures.  So let’s take a look:

deinocheirus-skull

I’m no expert, but I suspect that even if I were one I’d have difficulty making sense of this hadrosaurine (duck-billed) skull on an ornithomimid (ostrich-mimic) dinosaur known for its huge arms and ferocious-looking claws.

The upshot?  I can’t wait until there are some papers published on all this new Deinocheirus material.

Marine Megafauna MOOC Assignment: Common Paper Nautilus

As I mentioned earlier, I am taking Marine Megafauna: An Introduction to Marine Science and Conservation, a free online course through the coursera platform.  This work for this course has included two writing assignments.  The first — a short-answer exercise involving spatial data — didn’t lend itself to a blog post,  The second, however, does.
Here’s a summary of the assignment, copied verbatim from the course website:
This is a writing assignment that focuses on developing a “species profile” for a marine megafauna species that is accessible and understandable by a general audience. This profile should cover key knowledge about the species, including information on its taxonomy, physical appearance, life history, foraging and feeding habits, and any other unique or special characteristics that may be present. The profile will also include a brief biography of an expert who studies that species, and it will provide a list of three references to direct readers of this profile to further information.
And here’s what I wrote (edited slightly, primarily to include more links to relevant information).  In case you’re wondering, the numbers preceding the paragraphs correspond to a peer-assessment rubric.

COMMON PAPER NAUTILUS
Female Argonauta argo with eggs, courtesy of Bernd Hoffman via Wikimedia Commons.
(1) Argonauta argo, the common paper nautilus, is not a nautilus at all but rather an odd octopod.  It shows tremendous sexual dimorphism in terms of both size and another interesting feature: females may grow brittle, foot-long (30 cm) shells, while males are generally about a centimeter in length and are shell-less.  Aside from this marked sexual dimorphism, the shell of the female is remarkable for two more reasons:  First, the beautiful shell allows females to practice “gas-mediated buoyancy [pdf],” allowing them to live easily at the water’s surface.  And second, recall that the common paper nautilus is an octopod — it is, in fact, one of only a very few to sport a shell.
(2) The taxonomy of Argonauta argo is as follows:  Along with clams and scallops and such, argo is a mollusk.  Within the taxon mollusca, argo is classified along with the true nautiloids as a cephalopod.  Within cephalopoda, argo joins squids and cuttlefishes in the taxon coleoidea.  From there, we zoom into octopodiformes, then to octopoda — all octopuses! — then incirrata (because argo doesn’t have fins).  Next argo finally separates from most other octopuses in the taxon argonautioidea, from which we zoom still further to argonautidea.  Within argonautidea we finally find our genus and species: Argonauta argo, or the common paper nautilus.  Within the genus Argonauta are three other recognized paper nautiluses or argonauts: Argonauta hians (the muddy argonaut); Argonauta boettgeri (Boettger’s argonaut); and Argonauta nodosa (the knobby argonaut).
(3) & (7) Again, when it comes to size, the common paper nautilus is marked by very significant sexual dimorphism:  The female is commonly measured by her shell diameter, which may reach approximately 30 cm.  The shell-less male is only about a single centimeter long.  Argonauta argo commonly appears to range in color from white to pale brown, but because of its chromatophores it also possesses — and exercises — the ability to change color.  Argonauta argo is generally epipelagic, or surface-dwelling, which is rare for an octopod.  It has been identified across a wide range of tropical and temperate waters.  These waters include [pdf] the coasts of the west Pacific (from Japan to New Zealand), the east Pacific (from California to Peru), the west Atlantic (from Massachusetts to Venezuela), the east Atlantic (from Spain  to South Africa), as well as the Mediterranean and Arabian seas.  It appears that there is no population estimate for Argonauta argo — at least, I could identify none — but according to a University of Michigan database it is “very common but is rarely spotted by humans.”  Neither is there any plan for management of this species.  Perhaps due to its apparently robust worldwide population, the common paper nautilus has not been evaluated for any conservation status by the International Union for Conservation of Nature, nor does it appear in the CITES (Convention on International Trade in Endangered Species) database.  Argonauta argo has relatively little interaction with humans and presently does not seem prone to any anthropogenic threats.  In fact, it has been suggested that due to rising ocean temperatures, the common paper nautilus’s range is expanding — it has recently been found in waters (northern Spain, for example [pdf]) where it previously had not been observed.  That said, it may not be a stretch to hypothesize that human-caused ocean acidification poses a long-term threat to the female Argonauta argo’s calcareous shell — and therefore to the species’s surface-dwelling way of life, its shell-reliant reproductive method, and perhaps its very existence. (Indeed, this threat has been studied with respect to Argonauta nodosa.)
(4) Like most octopods, Argonauta argo is thought to have a short lifespan of no more than a few years. Its method of reproduction is similarly typical of octopods.  The tiny male’s third arm is what’s called a hectocotylus — essentially a combination arm and penis.  The male places his hectocotylus into the female’s mantle to deposit the his sperm (via a packet called a spermatophore) and fertilize her eggs.  This process generally ends in the separation of the hectocotylus from the rest of the male.  The female  stores the fertilized eggs in her shell.  Eggs are very small — under a millimeter in diameter — and numerous.  It is thought that, unlike most other octopods, females are capable of reproducing more than once; males, on the other hand, probably are more typical among their taxonomic “cousins” and die after reproduction (at which point they may well be eaten by their partners).
(5) We don’t know much for certain about the feeding habits of Argonauta argo.  According to a paper from 1992, a 1932 paper described the species eating small fish and crustaceans; a 1977 paper instead suggested a diet of small invertebrates like sea snails and sea butterflies.  That more recent (but still twenty-year-old) 1992 paper described a predatory attack by Argonauta argo on a jellyfish:  The argonaut first grabbed the jellyfish with the suckers of two arms, then took two bites with its hard beak.  The argonaut seems to have used these bites in an effort to reach the “gastral cavity” or stomach of the jellyfish so it could feed not on the jellyfish itself but rather on the plankton the jellyfish had eaten.  This foraging method makes a lot of sense for a surface-dwelling ocean resident that is likely a predator.
(5) It should also be noted that, like most octopods, Argonauta argo possesses a rasp-like tongue called a radula and likely some form of venom as well, so it has the physical capacity to eat crabs (a favorite of most octopods) even if its surface-dwelling lifestyle rarely affords such an opportunity.
(8) Dr. Julian Finn is an expert on marine invertebrates who specializes in the paper nautilus.  Dr. Finn wrote his doctoral thesis on the genus Argonauta and recently was lead author on the paper discussing the female Argonauta argo‘s use of her shell for buoyancy.  He currently works as a Senior Curator at the Museum Victoria in Melbourne, Australia (where he also completed his PhD research).  Additionally, Dr. Finn has worked as a freelance cameraman and consultant on many documentaries.
(9) Further Reading:
Finn, J. K., and M. D. Norman. 2010. The argonaut shell: gas-mediated buoyancy control in a pelagic octopus. Proceedings of the Royal Society B 277: 2967-2971.  http://rspb.royalsocietypublishing.org/content/early/2010/05/18/rspb.2010.0155.full.pdf
Guerra, A., A.F. Gonzalez and F. Rocha. 2002. Appearance of the common paper nautilus Argonauta argo related to the increase of the sea surface temperature in the north-eastern Atlantic.  Journal of the Marine Biology Association of the United Kingdom 82: 855-858. http://digital.csic.es/bitstream/10261/25147/1/download.pdf
Heeger, T., U. Piatkowski, and H. Moller. 1992. Predation on jellyfish by the cephalopod Argonauta argo. Marine Ecology Progress series 88: 293-296.  http://www.int-res.com/articles/meps/88/m088p293.pdf

The original assignment did not require a robust reference system. I’ve done my best to restore some sourcing, but If I’m missing anything obvious that deserves credit, please let me know.
Perhaps another time I’ll focus in more on the shell of the female common paper nautilus — this is a feature that seems quite unique and (figuratively) colorful.  Even absent any further delving on my part, though, I hope you’ll agree based on the information I’ve already provided that this “odd octopod” is interesting indeed.

Roger Williams Park Botanical Center

On Saturday my family and I visited the Botanical Center at Providence’s Roger Williams Park.  Here are some of the more interesting plants we saw:

To begin, here’s the fluffy flower of Calliandra haematocephala, also called the powderpuff tree or stickpea:

2014-03-02_01

Next up: the elephant cactus, Pachycereus pringlei, can apparently reach almost 20 meters tall! The Roger Williams Park cactus is so tall its top is tied to a ceiling rafter, but I was still more impressed by its spines:

2014-03-02_02

Cactus spines deserve their own post someday, but until that day here’s some fun reading on what spines are, exactly.

Aha! Here we have some species of sundew (Drosera) cohabiting a lovely little bog with some species of bladderwort (Utricularia — perhaps U. livida)!  Sundews capture insects and other small prey that lands on their many sticky tentacles. Utricularia, you might recall, suck small animals into bladders and eat them.  Both are tremendously impressive:

2014-03-02_03

For good measure, here’s a carnivorous pitcher plant too — I believe it’s a species of Sarracenia.

2014-03-02_04

Now here’s something new — a Begonia rex of the “Escargot” variety.  I don’t believe I’ve ever seen a leaf take this form before.  It looks like it crawled out of the sea:

2014-03-02_05

Before finishing up, let’s take a moment to marvel.  Cactus spines are likely modified leaves.  Sundews, bladderworts, and pitcher plants all developed traps — some active, some passive, all capable of capturing and digesting prey — that are highly modified leaves.  And the above Begonia rex “Escargot” sports leaf modifications of a different sort.  Perhaps that spiral shape is practical in some way I haven’t thought of, but regardless of utility it is quite beautiful.  All these structures are leaves, and wow! how different they are.

I started with a flower and I’ll end with a flower. This hibiscus stood out to me mainly because it made such a contrast to the cold, snowy outside visible through the greenhouse panes behind it.

2014-03-02_06

Ah, the promise of summer.

Utricularia Suck Small Animals Into Bladders And Eat Them

On December 2, 1874, the remarkable Mary Treat wrote to Charles Darwin:

I have been studying the bladder-bearing species of Utricularia off and on the last year, and am now fully satisfied that they are the most wonderful carnivorous plants that I have yet seen. The so-called little bladders seem to be receptacles for digesting animal food. Not only small animalcules are lured into these receptacles, but animals large enough to be distinctly seen with the naked eye; and by holding the little bladders up to the light the movements of the animals can be seen with the unassisted eye.

We’ll get to Darwin’s response in a bit, but for now let’s ask: just what are these wonderful bladder-bearing botanical beasts to which Treat was referring?

Utricularia is a genus comprising several species of carnivorous plants called bladderworts.  Most (but not all) of these are aquatic and capture their prey by the use of so-called bladder traps or “utricles.”

Utricularia traps, courtesy of Michal Rubeš via wikimedia commons.

According to a review article by Elzbieta Krol and colleagues, Utricularia‘s “[s]uction-traps (bladders) are ranked among the most complex leaf structures ever to have been examined in plants.”  The traps work like this: A plant’s bladder forces water out, creating a sort of vacuum within the bladder and stored energy potential in the bladder walls.  At one end of the bladder is a tightly sealed valve rimmed by several hairs.  These hairs act as triggers for the bladder trap.  According to Krol, “each trigger hair acts as a lever, breaking the seal and releasing the energy whenever something (living creature or strong current) disturbs it.”  In other words, a light tap on one of these hairs causes the bladder to suck whatever happens to be outside the valve into the bladder.  Inside, the captured prey becomes plant food.

These bladders are quite impressive when you consider what they can trap, as listed by Krol (referencing Darwin): “aquatic species [of Utricularia] can hold … substantial prey, such as crustacean zooplankton (e.g. water fleas), nematodes, mosquito larvae, insects, tadpoles and even small fish.”  Apparently, Krol notes, they also end up eating a lot of algae.

An aquatic plant with complex bladder traps that allow it to eat fish?  Mary Treat called it wonderful, Elzbieta Krol calls it “truly outstanding,” and I say it’s tremendously impressive.

And speaking again of Mary Treat, what of her correspondence with Charles Darwin?

In the months following Treat’s letter to Darwin, he published his book Insectivorous Plants and she published an article in Harpers Magazine titled “Is the valve of Utricularia sensitive?”  Darwin had apparently suggested in his book that Utricularia were passive feeders, while Treat very respectfully disagreed:

Mr. Darwin says the valve does not appear to be in the least irritable, and continues (Insectivorous Plants, page 408): “We may therefore conclude that the animals enter merely by forcing their way through the slit-like orifice, their heads serving as a wedge.” But we have seen in the instances of the mosquito and chironomus larvae [each of which was trapped tail-first] that this is not the case; the head does not serve as a wedge. But what is the force that impels them into the utricle? It seems too bad to try to overthrow a plausible theory and offer nothing better in its stead. But what can I do? The play is enacted before me, and I have tried in vain to get behind the scenes to learn what the power is that impels the larva into the utricle. No doubt if Mr. Darwin had had the excellent material that I had to work with, with his keener insight he would have ferreted out the cause.

If within the utricle was a partial vacuum, the sudden opening of the valve would create sufficient force to carry whatever happened to be in close proximity into the utricle; and this illustrates the movement we see executed. But how could a vacuum be formed?

Treat attempted to send Darwin some Utricularia specimens and her article; Darwin at first received the former but not the latter.  He responded colorfully:

The specimens which you have sent of Utricularia are most beautiful & excellently preserved. I shall feel great interest in reading your account of them when published.

I am sorry to say that I never received the article in Harpers on the sensitivity of the valve in Utricularia,— a subject which drives me half mad.— If you have been able to prove either side of the case, I beg you tell me exact title & date of the number, which I can then easily pursue.

About a month later, after another letter from Treat, Darwin read the article and wrote to her:

My dear Madam

I have received your kind letter & the article which I have read with the greatest interest. It certainly appears from your excellent observations that the valve was sensitive … but I cannot understand why I could never with all my pains excite any movement. It is pretty clear I am quite wrong about the head acting like a wedge.— The indraught of the living larvæ is astonishing. …

I am not well & am staying away from my home for rest, so pray excuse brevity. Wishing you success of every kind in your admirable work

I remain | Dear Madam | Yours very faithfully | Ch. Darwin

So there you have it.

P.S.  In the course of researching this post, I learned that there are native Utricularia — as well as Drosera (sundews) and Sarracenia (pitcher plants) — residing in Rhode Island’s wetlands.  I am excited to have new things to look for when tromping around outside this summer!

Reference:

Krol, E.; Plancho, B.J.; Adamec, L.; Stolarz, M.; Dziubinska, H.; Trebacz, K.  2011.  Quite a few reasons for calling carnivores ‘the most wonderful plants in the world. Annals of Botany 109 (1): 47–64.doi:10.1093/aob/mcr249