'Donts and 'Apsids: Ancestral Dinos and Mammals of the Mid-Triassic

When it comes to dinosaurs and mammals, neither had quite yet evolved yet.  Most people consider animals like Herrerasaurus and Eoraptor to be among the oldest known dinosaurs, but others now consider Nyasasaurus to be the oldest, originating from 240 MY old rocks from Tanzania.  Many dinosaurs looked very similar to other, closely related archosaurs, and only extensive research and more specimens will be able to shed light on these ancient critters.

Mammalian ancestors took the form of the now-extinct dicynodonts and the cynodonts, the latter of which include modern mammals, as well.  In modern mammals, you can see how the skull only has a single hole behind the eye (the space where the coronoid process sneaks in between the main part of the skull and the extruding zygomatic arch), making it a synapsid, or "one-holer."  In previous posts, we've talked about primitive, mammal-like animals such as Dimetrodon and Cotylorhynchus.  Both of these critters are synapsids.  Diapsids, or "two-holers" (remember from our recent Latin/Greek Roots post that the root "di" means "two" [click HERE to read that post]), is another large group, and includes everything from crocodiles to dinosaurs, lizards to snakes, and tuataras to birds.  It also includes the archosaurs, a subgrouping of diapsids that are characterized by an additional hole in the skull, bringing the total number of skull holes up to three.  So some diapsids are also archosaurs, such as birds, dinosaurs, and crocodiles.  There's also the anapsids, which are animals with no holes in the skull, such as amphibians and turtles.  Taxonomically, this can get a bit confusing (especially since sometimes an animals classification doesn't correspond to the number of holes that it has at that point in its evolutionary history), and maybe later we can go into greater detail about these different 'apsids, but below we have a nice picture that should help clear things up a little.

Holes in the skull.  On the top left, we have the prehistoric sea turtle Protostega, an anapsid, with no extra holes behind the eye socket.  Below Protostega, we have Prestosuchus, a type of archosaur.  Not only does Prestosuchus have the two holes in the skull behind the eye socket that characterize older diapsids, but it also has a third hole, in front of the eye socket, but behind the nose openings.  On the bottom right, we have Edaphosaurus, a primitive synapsid.  The largest hole in the skull, furthest on the right, is what will one day become the hole that the coronoid process sneaks through, between the zygomatic arch and the rest of the skull.  In the picture above Edaphosaurus, you can see what I'm talking about, with the extinct mammalian synapsid Hyaenodon.  Here, you can see the little nub of the coronoid process between the zygomatic arch and the skull.

As we talked about in that Latin/Greek post that I mentioned above, the name of the primitive, fin-backed synapsid Dimetrodon means "two measures of teeth," referring to the two different types of teeth this animal possesses.  This is a feature known as "heterodonty," a term that means "different teeth."  Most mammals are heterodonts, and most other animals like reptiles are not, but it doesn't always work that way.  Modern cetaceans such as the sperm whale, as well as orcas and dolphins, are homodonts, meaning that they only have one type of tooth in their mouth.  If you look at ancient ancestors of whales, such as Basilosaurus or Zygorhiza, you can see that they have different types of teeth in their mouth.  This condition can be traced all the way back to 50 MY old Pakicetus.

A trio of cetacean skulls.  On the top left, we have Pakicetus, a terrestrial ancestor of the cetaceans, that lived in Pakistan approximately 50 MYA.  Below Pakicetus, we have Zygorhiza, a more derived and fully aquatic cetacean.  In both Pakicetus and Zygorhiza, you can see how the front teeth and back teeth are different, with the front teeth more for gripping prey, and the back teeth perfect for slicing.  On the right, you can see the skull of the modern killer whale, or orca, which has only one type of tooth in their mouth, the conical, gripping teeth.

Then, of course, there are the heterodont reptiles and dinosaurs such as the Cretaceous crocodilian Malawisuchus, and the dinosaurs Heterodontosaurus (literally meaning "different-toothed lizard") and the oviraptorosaur Incisivosaurus.  We also talked about the primitive pterosaur Dimorphodon (two morphs of teeth) in the Latin/Greek post as well.  If you look at the skulls of any of these animals, you can clearly see the different types of teeth in their mouth.  Cynodonts were not merely an aberrant heterodont form amongst a vast sea of closely related homodonts, but instead were precursors to the default heterodont condition seen in mammals.

The skull of Heterodontosaurus, on display at the American Museum of Natural History in New York.  You can see the two different types of teeth in the skull, especially in the lower jaw.

Works Cited:

Whales In Music: An Interview With Alex Shapiro, Composer

So a month or two ago, I went down to Greeley, Colorado to see my good friend Masaki Kleinkopf perfom in the All State Concert Band.  One of the songs that they played there was a piece by composer Alex Shapiro entitled "Immersion."  One of the movements in the piece was entitled "Beneath," and it was particularly interesting!  In it, the band played with one of the most musical animals in the world: the whale!  I was very interested in this piece and the work that went into it, so I contacted the composer and asked her a few questions, and she was kind enough to oblige!  I found her answers very, very interesting, and I hope you guys find them as interesting too!

Alex Shapiro!  Photo Credit: Paul Chepikian

The Natural World:  What made you decide on including whale song in the piece?

Alex Shapiro:  Interestingly, the choice wasn't pre-meditated; the song found me, and I welcomed it in unexpectedly. To back-track for a moment, BENEATH-- for symphonic wind band and prerecorded electronics-- was originally a far more intimate piece for contrabass flute and that very same prerecorded electronic track, titled BELOW. Anyone curious can hear excerpts from both versions of the music: the original solo piece for contrabass flute and prerecorded electronics, BELOW:

http://www.alexshapiro.org/Belowpg1.html

And the version I later created, using the exact same track, for symphonic wind band, titled BENEATH:

http://www.alexshapiro.org/Immersionpg1.html

Around the same time that I was beginning to think about a commission from the wonderful flutist Peter Sheridan for what ended up becoming BELOW, I happened to be poking around on the NOAA Vents Program website (http://www.pmel.noaa.gov/vents/index.html), fascinated by the sounds from our oceans. If I weren't a musician, I might have become a marine biologist, and I also have a fascination with the geology of the ocean floor. I found-- and ended up using to open and close the piece-- a recording of a volcanic eruption from the floor of the Pacific. Perusing the NOAA website, I clicked through to the area with whale songs (http://www.pmel.noaa.gov/vents/acoustics/sounds_whales.html) and from there, I found my way to many other websites with marine mammal audio files. And that's how I discovered the whale who I realized would be a perfect duet partner with Peter. The song was so haunting, I just had to use it as the centerpiece of the music.

TNW:  What specific whale did you choose?

AS:  The recording I use is that of a male Pacific Humpback whale; I'm told that they're the ones who do the best singing. I actually listened to a couple of hundred whale songs from seven or eight different kinds of whales before I came across this heart-wrenchingly beautiful song. I became adept at hearing the differences in the vocalizations of each species, and could identify a Minke from a Blue from a Sperm just from the audio. Orcas-- the most familiar whales where I live on San Juan Island, Washington, are easy to discern because, as members of the dolphin family, they make high-pitched chirps. Like the Orcas, many whales don't have a song that lends itself as well to human composition needs when it comes to melody (I place the blame for this on the limitation of our musical language, not theirs!). Too many short blasts, pulses, and other non-linear sounds (all of which are great for rhythm, though!). But the Humpback really does sound much more like a human voice, and when I found this particular song, I was mesmerized. I went over to my piano and began improvising with it. Amazingly, the whale was perfectly pitched with my well-tempered instrument, and I immediately found harmonies that worked beautifully (thus making it a whale-tempered piece!). The only audio editing I needed to do was to use filters and equalization to "clean up" the sound of the audio file, so that the blanket of low-humming water noises picked up by the hydrophones that recorded the animal, didn't overpower the higher pitch of the song itself.

TNW:  Are you planning on incorporating nature motifs into any later pieces?

AS:  Absolutely! I'm often recording the sounds around me-- from nature, and even from my travels through and across nature, such as last week when I was on the ferry from Friday Harbor to Anacortes, on Fidalgo Island, and used my iPhone to capture a hypnotic rhythmic passage created by the boat engine that I'll use in an upcoming work. And one of my upcoming 2014 symphonic wind band commissions will be centered around recording the sounds of the state of Wyoming, and using them in the digital audio track I create to accompany the band. The possibilities are endless, and inspiring.

TNW: Where did you get the idea to do a piece about Wyoming? Have you already come up with the ideas for the sounds you are going to use?

AS: The piece is an upcoming commission for wind band and prerecorded electronics, commissioned in part by a grant from The Biodiversity Institute, a division of the Haub School of Environment and Natural Resources at the University of Wyoming, to be premiered by conductor Bob Belser and the University of Wyoming Symphonic Band, that will entail me returning to Wyoming to capture the sonic essence of the environment. U of Wyoming gave a beautiful performance of IMMERSION last year (the piece that includes BENEATH, with the whale), and and you can imagine, this new piece is a perfect fit for me!

And again, anyone curious can hear excerpts from both versions of the music: the original solo piece for contrabass flute and prerecorded electronics, BELOW:

http://www.alexshapiro.org/Belowpg1.html

And the version I later created, using the exact same track, for symphonic wind band, titled BENEATH:

http://www.alexshapiro.org/Immersionpg1.html

I would like to take this opportunity to thank Ms. Shapiro for taking the time out of her busy schedule to chat with me!  Hopefully we can ask a few more questions for her once her Wyoming piece is released!  I feel as if I speak for all of us when I say we look forward to hearing more from her in the future, both blog-wise and music-wise!