Taking Wing

Taking Wing

June 20, 2010, 6:11 pm
Filed under: Uncategorized | Tags: bird, ceratosaurus, Dinosaur, dinosaur renaissance, Dragons of Eden, Richard Owen

 Part 1 – Preliminaries 

Like vintage Pulp covers or Japanese Kaiju films from the 50s, old-school Dinosaur panoramas (ala Zallinger’s Age of Reptiles) have a quaint and quirky sort of charm about them. Some of them are as full of myth and scientific inaccuracy as any medieval bestiary – but that, I suppose, is part of their appeal. Reproduced below is the cover art from Carl Sagan’s 1977 publication ‘The Dragons of Eden’. The illustrator is Donald Davis.

 

1- Ceratosaurus, 2-Troodon(?), 3-Archaeopteryx(?)

Witness a ponderous Ceratosaur (1) lugging its tail up a grassy incline in the distance. Popular depictions of large dinosaurs as sluggish, tail-dragging creatures were commonplace during the 70s, and this cover illustration is no exception.

 The idea that dinosaurs were clumsy, maladapted tail-draggers is as old (it enjoyed widespread scientific popularity for well over a hundred years) as it is false. Paleontology and Geology were still underdeveloped sciences when the first complete dinosaur skeletons were unearthed in the mid-1800s. Back then, the fossil record was woefully impoverished* – a yawning abyss punctuated by the occasional fossilized body part (teeth, femurs, vertebrae etc.) or partial skeleton. Only a few score fossil genera had been scientifically described when Darwin first began composing his seminal treatise in 1858**  and it would take many more years of excavation and careful study for any nominally consistent narrative of vertebrate history to emerge from the hallowed halls of academia. Unsurprisingly, many early theorists in the field of dinosaur science (anatomists by trade) suffered from a kind of temporal parochialism that would seem obscene to the modern-day paleontologist: all extant reptiles are slow and sluggardly creatures and therefore, they reasoned, all extinct reptiles (including Dinosaurs) must have been too.*** Even in the mid-19th century, however, this notion was not entirely without its detractors. As early as 1841, a reputable British anatomist by the name of Richard Owen suggested that Dinosaurs were active, warm-blooded animals. We will deal with Owen’s assessment in some detail later on in this series.

Victorian misconceptions often die hard and it took a small-scale scientific revolution – spearheaded by John Ostrom, Robert Bakker and others in the late- 1960s – for researchers to finally start reassessing and reworking their antiquated theories on dinosaur physiology and behavior. Several independent lines of evidence now suggest that the Ceratosaurs and their bipedal, flesh-eating cousins held their tails off the ground and led relatively active lifestyles.

From “living tripod” to fleet-footed hunter: Changing perceptions of Ceratosaurus

 Interestingly, this modern view of Dinosaur behavior seems to be reflected in Davis’ portrayal of the diminutive Troodon**** (2) as a lithe, bird-like social predator. 

Soaring far above this idyllic hillscape is the verdant figure of a primitive, long (and presumably bony) tailed bird (3). My best guess is that this winged creature is a rather fanciful reimagining of the celebrated Archeopteryx lithographica – which was, as far as I am aware, member to one of only three Mesozoic bird genera known to science prior to the 1980s. In reality, Archeopteryx was approximately the same size as the European magpie and it almost certainly did not glide at great altitudes as the illustration in question seems to suggest. 

This series will concern itself with the origins and early evolution of the birds. Archeopetryx will play a prominent role in our enquiry and a considerable chunk of the text that follows will be devoted to carefully examining and describing this remarkable species of bird. 

Before we go traipsing about the sunlit fields of Davis’ Garden of Eden in search of our feathered quarry, perhaps it would be wise to briefly set down some general observations on the external anatomy of the Aves. Here I will defer to a man who was, ostensibly, the world’s first natural historian and an indefatigable bird-watcher to boot. 

NOTE: Turgid. Confusing. Unpolished. Such adjectives are used time and again to describe much of the surviving Aristotelian corpus. But is such verbiage warranted? Judge for yourself. Below are excerpts from one of Aristotle’s zoological researches, the Historia Animalium. The exerpts have been edited for the purposes of brevity and certain sentences have been bolded for emphasis.

“Birds have in all cases a head, a neck, a back, a belly, and what is analogous to the chest. The bird is remarkable among animals as having two feet, like man; only it bends them backwards as quadrupeds bend their hind legs. It has neither hands nor front feet, but wings-an exceptional structure as compared with other animals. Its haunch-bone is long, like a thigh, and is attached to the body as far as the middle of the belly; so like to a thigh is it that when viewed separately it looks like a real one, while the real thigh is a separate structure betwixt it and the shin. Of all birds those that have crooked talons have the biggest thighs and the strongest breasts. All birds are furnished with many claws, and all have the toes separated more or less asunder; that is to say, in the greater part the toes are clearly distinct from one another, for even the swimming birds, although they are web-footed, have still their claws fully articulated and distinctly differentiated from one another.
Birds are furnished with a mouth, but with an exceptional one, for they have neither lips nor teeth, but a beak. Neither have they ears nor a nose, but only passages for the sensations connected with these organs: that for the nostrils in the beak, and that for hearing in the head. Like all other animals they all have two eyes, and these are devoid of lashes. The heavy-bodied (or gallinaceous) birds close the eye by means of the lower lid, and all birds blink by means of a skin extending over the eye from the inner corner; the owl and its congeners also close the eye by means of the upper lid. The same phenomenon is observable in the animals that are protected by horny scutes, as in the lizard and its congeners; for they all without exception close the eye with the lower lid, but they do not blink like birds. Further, birds have neither scutes nor hair, but feathers; and the feathers are invariably furnished with quills. They have no tail, but a rump with tail-feathers, short in such as are long-legged and web-footed, large in others. These latter kinds of birds fly with their feet tucked up close to the belly; but the small rumped or short-tailed birds fly with their legs stretched out at full length. All are furnished with a tongue, but the organ is variable, being long in some birds and broad in others. Certain species of birds above all other animals, and next after man, possess the faculty of uttering articulate sounds; and this faculty is chiefly developed in broad-tongued birds.” 

 

Aristotle, the philosopher scientist.

 As a philosophy writer, Aristotle strove for clarity and simplicity rather than literary finesse. His unembellished, dialectical prose-style and his penchant for repitition can sometimes make his texts a chore to read. This is not to say that he was a lousy thinker. To the contrary, few intellectuals from any succeeding age could claim to have possessed the sheer breadth of his erudition – he wrote with equal authority on disciplines as diverse as literary criticism, Ethics and Biology. Although few of his ideas carry any serious scientific weight today, he left a tangible intellectual footprint on the early history of almost every field of rational enquiry one could care to name. Some of the those footprints took centuries, if not millenia, to fade away.

To be continued …

* The only exceptions to this rule included the fossil record for various members of the Pleistocene megafauna and certain groups of marine Reptiles.  I  am also discounting all genera that are now considered invalid.

 

** Coincidentally, 1858 was also the year one of the first nearly-complete dinosaur skeletons – the Haddonfield Hadrosaurus – was excavated.

*** I have grossly oversimplified their contentions here, but rest assured, we will deal with them more fully in due time.

**** Although it could well be some species of Dromeosaur. Sagan’s book, however, devotes more than a few sentences to Troodontid intelligence – and hence, I have no qualms about calling this large-headed, gracile creature a Troodon.

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