About Me

My Photo
I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

31 August 2012

Thanks for all the flowers, Pterosaur!

Try to imagine a world without flowers. That would just suck, wouldn't it? What the heck would we give to our loved ones for romance or grieving... ginkgoes, ferns, pines? Sorry gymnosperms, but, no. Just, no.

Flowers are one of the things that make life worth living, especially for us primates. Were it not for their bright colors and rich scents acting as selection pressures, we likely would never have evolved at all.

And it looks like we can thank pterosaurs for that, at least indirectly. As if there weren't enough reasons to love them already.

Flowering plants first radiated in the Early Cretaceous, and appear to have sparked a global explosion of faunal diversification that, in many ways, created the modern ecosystem. Sometimes called the Cretaceous Terrestrial Revolution, this period of time between 125 to 80 million years ago witnessed the replacement of gymnosperms by angiosperms in almost all ecosystems. This, in turn created new opportunities and challenges for terrestrial animal life, and the result was an explosion of new forms. Bees appeared for the first time. Leaf-eating flies, butterflies and moths underwent rapid diversification, as did lizards, snakes, and basal groups of birds and placental mammals (that would be us lot).

Dinosaurs weren't left out of this party, either (though there is some dispute about whether their apparent explosion of diversity is just the result of sampling bias in the fossil record). This was the heyday of the hadrosaurids, ankylosaurids, neoceratopsians, carcharodontosaurines, ornithomimosaurids, troodontids, and dromaeosaurids.

The  role of the pterosaurs in this exciting period has been largely tabula rasa, thanks in no small part to the lack of a robust fossil record for these totally awesome creatures, the first of the flying amniotes. But that's all changed in the last couple of decades, which has witnessed an explosion of pterosaur fossil finds to rival the early period of dinosaur paleontology. It sometimes seems like a new pterosaur is being discovered every month.

Last month's contestant was Europejara olcadesorum, the oldest tapejarine pterosaur yet discovered. The age of the fossil, and its co-occurence (along with other tapejarids) at some of the earliest known angiosperm sites, suggests the intriguing possibility that these far-flying pteros may have played an important role in the worldwide spread of flowering plants, by acting as proficient pollinators.


Coloured head crests
The Pterrific Pterosaurs, by Luis Rey


"Now, hold on, HH," you might be saying. "You lost me at 'tapejarine.' What are you on about? Isn't a pterosaur just a pterodactyl? And didn't they, like, eat fish or something?"

Well, dear returning reader, pterodactyls were indeed pterosaurs, but that doesn't mean all pterosaurs were pterodactyls (or, for that matter, pteranodons... who also weren't pterodactyls). No mere flying dinosaurs were these! In fact, they weren't dinosaurs at all.

The pterosaurs diverged from their common ancestor with dinosaurs sometime in the Early Triassic. No one is quite sure when, because the gorgeous creatures are so highly derived that it's difficult to tell what their common ancestor might have looked like. There are a few candidates for the  vaunted title of "early pterosaur terrestrial relative," but none of them are satisfactory. Sorry, Scleromochlus taylori and Sharovipteryx mirabilis, but I don't make the rules.

By the Jurassic, though, pterosaurs had radiated into an amazing array of forms (also, see the cool painting above by the inestimable Luis  Rey), broadly divided into two groups: the rhamphorhynchoids, also called the long-tailed pterosaurs; and the pterodactyloids, also called the short-tailed pterosaurs. Tapejarines are nested within a group of large-bodied pterodactyloids called the Azhdarcoidea, named after a dragon in Uzbek legend.



Image: Tapejara pterosaur
Dmitry Bogdanov/Getty Images

Tapejarines are interesting for a lot of reasons, one of them being that they're usually interpreted as having been fruit- and seed-eaters, quite a departure from the popular image of pterosaurs as dealers of winged death, swooping down to carry off defenseless prey. To be sure, most pterosaurs were predators, but I give tapejarines pride of place because their apparent frugivory so wonderfully demonstrates the Darwinian insight of "endless forms most beautiful."

To some people's eyes, the tapejarines resembled giant toucans or parrots with impressive head crests. Europejara was no exception; her short "beak" is exactly the kind of thing we find on birds adapted to fruigvory and granivory.  And her age and locale indicate a pretty darn good reason: pterosaurs exploited the new niches created by angiosperms, just like all the other folks at the Cretaceous Terrestrial Revolution party.

What's more, preliminary evidence suggests the tapejarines may not simply have adapted to the new kinds of plants, but may also have played an important role in their early radiation:
tapejarines and early flowering plants display synchronic radiation events and similar patchy geographic distributions that appear to covary (i.e. temporal and spatial congruence). In light of this, the Barremian–Aptian distribution of tapejarines might be partially associated with the first radiation phase of the early angiosperm plants occurring at that time in both hemispheres.
To put that in paleo-nerd talk, it looks like tapejarine pterosaurs deserve some mad props not just for the evolution of the rose you gave that pretty girl, or of the fruit you had at your luscious vegan breakfast, but also of the pretty girl herself. And of you.

Much love, pterosaurs, and thanks for all the flowers.


thumbnail
Figure 2. Line drawing of the holotype of Europejara olcadesorum gen. et sp. nov. and life restoration.(A) Interpretative line drawing of the skull as observed on the acid-prepared counterslab. (B) Reconstruction of the skull (based in part on Tapejara) showing preserved parts in red. Life restoration of the head of Europejara in lateral (C) and frontal (D) views. apj, anterior process of the jugal; aprj, anterior process of the right jugal; d, dentary; ec, ectopterygoid; hy, hyoids; j, jugal; l, lacrimal; ld, left dentary; lj, left jugal; lm, left maxilla; lpo, left postorbital; lq, left quadrate; lsa, left surangular; lsq, left squamosal; ltf, lower temporal fenestra; m, maxilla; naof, nasoantorbital fenestra; o, orbit; pf, postfrontal; po, postorbital; pt, pterygoid; q, quadrate; rap, retroarticular process; rd, right dentary; rm, right maxilla; scd, sagittal crest of the dentary; scp, scleral plates; sq, squamosal. Scale bar: 50 mm.
doi:10.1371/journal.pone.0038900.g002


thumbnail
Figure 7. Distribution through time and space of tapejarine pterosaurs and early angiosperms.(A) Early Cretaceous (Aptian) paleogeographical map showing the three main areas where tapejarids co-occur with early angiosperms (black stars). (B) Stratigraphic distribution of the different tapejarid taxa (silhouettes above each taxon denote geographical occurrences); note that the diversification of tapejarids coincides with the Phase I of the early angiosperm diversification (EAD) [60][62]. (C) Leaves of an early angiosperm (cf. Jixia) from the late Barremian of Las Hoyas (MCCM-LH 30351), one of the oldest known macrofossil of a terrestrial flowering plant. Early angiosperm pollen grains Afropollis (D) and Stellatopollis (E) from the La Huérguina Formation, both worldwide distributed during the Barremian–Aptian interval. Ber, Berriasian; Val, Valanginian; Hau, Hauterivian; Bar, Barremian; Apt, Aptian; Alb, Albian; Cen, Cenomanian; Tur, Turonian; Con, Coniacian; San, Santonian; Cam, Campanian; Maa, Maastrichtian. Scale bars: 10 mm (C) and 10 µm (D,E).
doi:10.1371/journal.pone.0038900.g007




2 comments:

  1. Wanted to share this awesome bbc series :

    http://www.youtube.com/watch?v=JX_Wo0xSfcg&list=PL34F8F5F43BE1FFA4&index=1&feature=plpp_video

    ReplyDelete
  2. Wow, that is an awesome doc, Idan. Thanks for the link. I'm gonna post the whole series on my main blog.

    ReplyDelete