Art. LXIX.—On the Affinities of Harpagornis: a Letter to Professor T. Jeffery Parker
[Read before the Otago Institute, 8th October, 1895.]
It has given me great pleasure to do for your friend Mr. Hamilton what you requested of me in your valued letter of the 14th ultimo, just received. His excellent photographs of the bones of Harpagornis, which came safe in your letter, were studied by me with interest. I mounted all six of them on cards, and yesterday compared most carefully all the characters they presented with a number of American raptorial birds and others. I also compared what Haast had to say on Harpagornis in the “Transactions of the New Zealand Institute,” vol. vi., 1873.
Without any doubt whatever, Harpagornis has among existing birds its closest allies among the true eagles, and the relationship is by no means very remote. I compared it with a skeleton of Aquila chrysaëtos, also with Thassaëtus pelagicus and Haliæetus leucocephalus and others. In various parts of its skeleton Harpagornis exhibits characters found in any one of these several genera, and about in the same proportion: that is, in a number of characters it agrees with Aquila, with Thassaëtus in an equal number, and so on for Haliæetus and others. It had a narrower skull in proportion to its length than has any modern existing eagle known to me. The pre-acetabular region of the pelvis of Harpagornis was also very short, but this is a common character in many extinct birds. Having fenestræ in the sternum means but little among eagles, as they may or may not be present in individuals of the same genus. Moreover, I have seen sterna of eagles wherein the fenestra occurred upon one side of the carina and not upon the other.
It is perfectly safe to say that Harpagornis represents a more or less generalised aquiline type, and might easily have been the common ancestor to a number of genera of existing modern eagles, as, for example, Haliæetus, Aquila, and Thassaëtus. In any natural scheme of classification it might, with the greatest propriety, be placed between the genera Aquila and Thassaëtus, and it would be standing as near where it belongs as we can possibly show at the present time.