Rigor Vitae: Life Unyielding

Wednesday, March 08, 2006

MAKING AN ASS OF U AND ME

A new exhibit at the University of California, Berkeley's Valley Life Sciences Building features the cast of a foot-long Triceratops horridus skull, thought to have belonged to a year-old, three-foot long individual. The skull was recently unearthed from Montana's Hell Creek Formation, and represents the youngest-known Triceratops. I was shocked to see the well-developed horns and frill in the photograph. Such adornments are usually absent in newborn vertebrates, and don't fully manifest themselves until sexual maturity. In the current issue of the Journal of Vertebrate Paleontology, UC Berkeley paleontologist Mark Goodwin states:

"The baby Triceratops confirmed our argument that the horns and frill of the skull likely had another function other than sexual display or competition with rivals, which people have often argued, and allows us to propose that they were just as important for species recognition and visual communication in these animals."

In addition to that, it suggests to me a complete lack of parental care, necessitating early development of defensive capabilities.
As a nature artist, I often have to make assumptions to make up for knowledge I lack, and sometimes find that I've painted a lie. Such may be the case with the ceratopsian pups in the two accompanying paintings, with rudimentary horns and frills, guarded by their parents. Painting paleo reconstructions requires the making of many assumptions. Like Goodwin, I assume that ceratopsian frills served as social signals, and I gave them bold colors or patterns. Likewise, I painted the rigid Dromaeosaurus tails blue, assuming yet another visual social signal. These dinosaurs are thought to be closely related to the line that gave rise to birds, and I gave them little “feather boas.”
Mistakes like my smooth-headed ceratopsian pups are forgivable, but I sometimes catch myself making wrong assumptions about contemporary nature, too, as I did in the painting above, based on memories of Cameroon's Korup Forest, where I observed a Chestnut-backed Owlet (Glaucidium sjostedti) on several occasions. This bird is a much larger version of the Northern Pygmy Owl (G. gnoma), an American bird that I know rather well. In Utah, Pygmy Owls are bold predators that often tackle very large prey, and, assuming the African bird had similar habits, I paired her with a bird I had seen in the same area and mis-identified as a Red-billed Wood-hoopoe (Phoeniculus purpureus). Some years after painting the piece, I learned that Chestnut-backed Owlets appear to eat mostly insects, and certainly not Red-billed Wood-hoopoes; the ranges of the two species are not known to overlap. The Wood-hoopoes I saw in Cameroon were probably the closely related P. bollei, which has a buff cap. Oops.

POSTSCRIPT: Speaking of making an ass, I just now noticed the smaller skull in the lower-left portion of the top photo. That is the yearling Triceratops, which is shown next to the skull of an adult for comparison. The horns and frill are still bigger than I would have expected, but I'm no longer shocked. Oops is right.
___________________
upper: Photograph from Science Daily
second: Totosaurus Herd--detail (1997) acrylic 15" x 10"
third: Chasmosaurs vs. Dromaeosaurs-- detail (1991) acrylic 20" x 30"
lower: Chestnut-backed Owlet & Red-billed Wood-hoopoe (1996) acrylic 7" x 9"

8 Comments:

Anonymous Roger B. said...

If Triceratops were born with horns and skull frills, it raises potentially interesting questions about how these features grew and as the animals aged. Any idea what the horns were made of?

2:21 PM  
Blogger cpbvk said...

Agreed. The adult horns were similar to cattle horns: long, bony protuberances of the skull that supported an outer keratinaceous covering. I would guess the young Triceratops grew those horns in the first year after hatching, but we've already established how good I am at guessing these things. The males of a number of Chameleon species have similar horns. Some of these hatch from eggs, others are born live. None of them start to to develop horns until they're far more developed than the little guy on display at UC Berkeley.

2:36 PM  
Anonymous Neil said...

I'm gonna have to get down to the Cal science library to check that little guy/girl out.

Baby rhinos have small horns. Of course rhino horns are quite morphologically distinct from ceratop(s)ian horns.

Horn development in both bovids and giraffe/okapi begins before sexual maturity.

11:45 AM  
Blogger cpbvk said...

Thanks for the link to the young White Rhino pic, Neil. It gives a good perspective. I'd guess that rhino is at a similar developmental stage as the young Triceratops, and his horn development looks roughly the same. Here's a shot of a ten-day-old Indian Rhino I took at the Nat'l zoo. (Mature Indian Rhinos have much shorter horns than do Whites). His horn is visible as a mere bud. This post was based on my having completely misinterpreted the Triceratops photo (boy is my face red), and I no longer feel like my ceratopsian paintings are necessarily far off the mark. Fun discussion, though.

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