Seeing the First Birds

Body without tail streamers

Confuciusornis has an interesting body. It is certainly that of a bird, but it also has some last vestiges of its ancestors and, like many birds, has some interesting plumage which, thankfully, has been saved by its fossils. If the feathers hadn't been saved who knows what the Chinese farmer and the paleontologists he called would have thought he had found. The thing about the plumage on Confuciusornis is that it can be deceptive. As was mentioned in yesterday's quick blurb, there have been Confuciusornis found with and without large tail feathers.The two streaming feathers have caused a bit of debate that has multiple points. Point one is that birds molt. All birds at some time of the year molt a bit. We shed skin, not as much at a time as a lizard, horses grow winter coats, birds molt. Fact of life. However, not all birds molt at the same time and even in a species the male and female may molt at different times of the year. It is therefore the assumption of point one that any and all Confuciusornis fossils found without the tail streamers are birds that are in the process of molting and growing new tail streamers. That being understood, we can move on to point two of the argument. Point two states that animals, though not all animals, possess a level of differentiation in which the animals within a species, think humans here for a moment, can tell apart individuals and, specifically, can tell male from female whether that is with voice, coloration, or other bodily adaptation. Therefore, it is the argument of those using point two as the basis for their conclusion that sexual dimorphism, the ability to tell the sexes apart based on unique bodily adaptations or ornamentations, even voice, is apparent in the possession or lack of the two streaming tail feathers found on some but not all fossils of Confuciusornis.

Body with tail streamers

Then, there is point three. Point three is, as a third party is in government typically, that there is a bridge between the two theories. This third point, therefore, admits that some of these fossils may indeed be the simple result of molting but that they may also show a level of sexual dimorphism via the streaming feathers of the tail. Personally, I believe point three allows us to view the hundreds of recovered Confuciusornis as a full spectrum of life; both male and female are represented as well as their molting habits. The only thing we are really and truly missing, should that be the case, is easily identifiable clutches of eggs and hatchlings and true juveniles of Confuciusornis. If those are found in abundance and well studied we may very well know this animal from birth to death and almost have a complete knowledge of a fossil animal minus the soft tissues which we do not have available to dissect and study.

©Daniel Bensen

This, therefore, brings me to a fantastic piece of art. In true 19th. century form, this bodily representation of C. dui has been laid out like a naturalist has just finished cataloging and inspecting the bodies of a male and female (or molted and un-molted if you prefer) Confuciusornis. This does a number of things for us. First of all it gives us an amazing look at, at least an interpretation, of the form of the body and a vivid color scheme which may have existed and beneficial to a bird at a time when flowering plants were just beginning to diversify the landscapes colors. Secondly, we have here a level of accuracy with the shape of the body that is very high and can thus picture this crow sized bird even better as a living and flying animal as it darts from tree to tree. The variations in color from male to female are what we typically expect in birds that show feathers as part of their blueprint for sexual dimorphism (reference the peafowl if you need to here) and the bill of C. dui is accurately detailed, which is important. Though there may be some detractors which say, and I do not know that there are for certain but someone always disagrees with what someone else says, it's inevitable, that some of the species of Confuciusornis are merely growth stages of the type species.

Here you can see that the bill of C. dui is sloped upward which may have been good for any number of reasons that we do not fully understand and obviously was good for at least one specific role in the Early Cretaceous forests and plains of China or it would not have developed and been present in a successful species in multiple specimens. Having trouble coping with that idea? Please look at this for a second and think about how life has a history of repeating itself when it finds something successful. I would venture to guess that the sloping upward of the bill in C. dui is in some way related to insect predation, like perhaps the insects on which this species fed liked to tunnel upwards into tree bark and an upturned beak would have allowed it to grasp the silly insects in their upward facing tunnels. Compare this beak, though, with the beak of the type species, C. sanctus. The bill of C. sanctus, the lower set of Confuciusornis, again male and female represented, in the above illustration, have hardy seed crunching beaks made, it appears, for opening large resilient seed casings to get at the meat inside. Some birds have been removed or are potentially being removed from Confuciusornis based on the bills, but in that case, I refer us back again to Darwin's Finches. Something to think about with the remainder of your Saturday!