Much had naturally been expected from the study of fossil birds, but, so
far as the making of classifications is concerned, they have proved
rather a source of perplexities. So long as the characters of new fossils
are only of specific and generic value, it is mostly possible to assign
the birds to their proper place, but when these characters indicate new
families or orders, for instance Hesperornithes, Ichthyornithes,
Palaelodi, their owners are put outside the more tersely constructed
classifications applicable to modern birds. It is no exaggeration to say
that the genus, often even the species, can be determined from almost any
recent bone, but in the case of Miocene, and still more, of Eocene
fossils, we have often to deal with strange families, which either
represent an extinct side branch, or which connect several recent groups
with each other. Our artificially-established classifications collapse
whilst we gain further insight into the mutual affinities of the existing
groups. Of course this must be so if evolution is true. But it also
follows that, if every extinct and recent bird were known, neither
species, nor genera, nor families, nor orders could be defined. We should
be able to construct the pedigree of every group, in other words, the
gigantic natural system, but there would be no classification. Much light
has also been thrown by fossil birds upon the study of geographical
distribution. The key to the distribution of recent groups lies in that
of the extinct forms. Not only have many absolutely new families been
discovered, but many kinds of modern birds are now known to have existed
also in countries which they are now extinct. There were, for instance,
trogons, secretary-birds, parrots, and other now Ethiopian forms in
Miocene France. Ostriches, undistinguishable from _Struthio_, have been
found in Samos and in the Sivalik Hills.
The proper study of fossil birds may be said to have begun with A.
Milne-Edwards, whose magnificent _Oiseaux fossiles de la France_ was
published from 1867 to 1871. This work deals chiefly with mid-Tertiary
forms. A new impetus was given by O.C. Marsh, who, after 1870,
discovered a great number of bird remains in the Cretaceous strata of
North America. The most important result is the proof that, until the
end of the Cretaceous epoch, most, if not all, birds were still
possessed of teeth (see ODONTORNITHES).
The oldest known bird is the _Archaeopteryx_ (q.v.), of the upper Oolite
in Bavaria. The imprints in the enormously older new red sandstone or
Lower Trias of Connecticut, and originally named _Ornithichnites_,
belong to Dinosaurian Reptiles.
A wide gap separates _Archaeopteryx_ from the next order of fossil birds
of the Cretaceous epoch, and, since freshwater deposits of that age are
rare, bird remains are uncommon. Many bones formerly referred to birds
have since proved to belong to Pterodactyls, e.g. _Cimoliornis_ from the
English Chalk. But in 1858 were discerned in the Upper Greensand of
Cambridgeshire remains which are now known as _Enaliornis_. W. Dames has
described bones from the Chalk of southern Sweden under the name of
_Scaniornis_, probably allied to _Palaelodus_. From the Cretaceous rocks
of North America a large number of birds have been described by O.C.
Marsh. Of these the most interesting are _Ichthyornis_ (= _Graculavus_)
and _Hesperornis_, from the Cretaceous shales of Kansas. They were
placed by Marsh in a distinct subclass of birds, _Odontornithes_ (q.v.).
Probably all birds of Cretaceous age were still possessed of teeth.
_Baptornis_, another of Marsh's genera, seems to be allied to
_Enaliornis_, _Palaeotringa_ and _Talmatornis_, were by him referred to
Limicoline and Passerine birds. _Laornis_ from the Cretaceous marls of
New Jersey was as large as a swan.
[Illustration: FIG. 17.--Remains of head of _Odontopteryx_, from the
original in the British Museum; side view; natural size.]
[Illustration: FIG. 18.--Remains of head of _Odontopteryx_, seen from
above.]
The lower Eocene has furnished a greater number of bird bones. Some of
the largest are those of _Gastornis_, with three species from France,
Belgium and England. Much difference of opinion obtains as to the
affinities of these birds, which were far larger than an ostrich; they
were undoubtedly incapable of flight and there are indications of teeth
in the upper jaw. Provisionally this genus has been grouped with the
Ratitae, which at any rate are a heterogenous assembly. Sir R. Owen's
_Dasornis_, of the London Clay, known from an imperfect cranium, and
E.D. Cope's _Diatryma_ of New Mexico, based upon a gigantic metatarsus,
may also belong there. The London Clay of South England has likewise
supplied some long upper arm bones, _Argillornis_. The most remarkable
specimen is a skull, _Odontopteryx toliapicus_ (figs. 17, 18); the edges
of the jaws were serrated like those of certain tortoises. The character
of this skull and the compound rhamphotheca (known by the imprints left
upon the jaws) indicate affinities with the Steganopodes. Remnants of a
heron-like bird, _Proherodius_, of a gull-like creature, _Halcyornis_, a
raptorial _Lithornis_; and a supposed Passerine from Glarus in
Switzerland, called _Protornis = Osteornis_, complete the list.
The upper Eocene has yielded many birds, most of which are at least
close forerunners of recent genera, the differentiation into the leading
orders and families being already well marked, e.g. Gallinaceous birds,
stork- and crane-like waders, rails, birds of prey, cormorants, &c.
Especially numerous bones have been found in the Paris basin, chiefly
described by G. Cuvier, F.L.P. Gervais, E. Blanchard, and above all by
A. Milne-Edwards, and in the equivalent beds of Hampshire. Others have
been discovered in Wyoming; a giant penguin, _Palaecudyptes_, is known
from New Zealand, and _Palaeospheniscus_ from Patagonia. The Miocene has
yielded by far the greatest number of bird-bones, including even eggs
and imprints of feathers. For instance, from the lower Miocene beds of
Allier and Puy-de-Dome Milne-Edwards has described about 50 species. Of
these _Palaelodus_ was an ancestral flamingo, but with shorter legs;
_Limnatornis_ is referred to the hoopoes. The existing genera include
_Anas, Aquila, Bubo, Columba, Cypselus, Lanius, Picus, Phalacrocorax,
Sula_, &c. Very interesting is the fact that _Serpentarius, Psittacus_
and _Trogon_ are amongst this list of birds, which are now restricted to
the tropics. A similarly mixed avifauna has been found in the
mid-Miocene beds of various other parts of France, Germany and Italy. In
Colorado and New Mexico Marsh has detected bones of _Meleagris,
Puffinus, Sula_ and _Uria_, all existing genera; but the first is
especially suggestive, since it is one of the most characteristic forms
of the New World.
Here may be interpolated a short account of the very peculiar avifauna
found in the Tertiary strata of Santa Cruz in Patagonia. Instead of the
age of lower Eocene, as had been stated originally, these beds are not
older than mid-Miocene, and not a few of the bones are of a much
younger, even latest Tertiary date. Discovered, and partly described, by
F. Ameghino, the bones have been sumptuously monographed by F.P. Moreno
and A. Mercerat, who proposed for them the name of _Stereornithes_, a
new order of birds, mostly gigantic in size, and said to combine the
characters of Anseres, Herodiones and Accipitres. But the whole mass of
bones is in hopeless disorder, apparently without any record of
association. At any rate, the "_Stereornithes_," accepted as such in
Bronn's _Thierreich_, and in Newton's _Dictionary of Birds_, had to be
dissolved as an unnatural, haphazard assembly. Many of these birds, to
judge from the enormous size of their hind-limbs, were undoubtedly
flightless, e.g. _Brontornis_, and remind us of the Eocene _Gastornis_
of Europe. _Phororhacos_, the most extraordinary of all, belongs to the
Gruiformes, perhaps also _Pelecyornis_ and _Liornis_. On the other hand,
the late Tertiary _Dryornis_ is a member of the Cathartae or American
vultures, and _Mesembriornis_, likewise of late Tertiary date, is a
close forerunner of the recent genus _Rhea_.
Pliocene remains are less numerous than those of the Miocene. From
Pikermi in Greece is known a _Gallus_, a _Phasianus_ and a large _Grus_.
From Samos a large stork, _Amphipelargus_, and a typical _Struthio_;
from the Sivalik Hills on the southern flanks of the Himalayas also an
ostrich, and another Ratite with three toes, _Hypselornis_, as well as
_Leptoptilus, Pelecanus_ and _Phalacrocorax_. The fossil egg of a
struthious bird, _Struthiolithus_, has been found near Cherson, south
Russia, and in north China. The Suffolk Crag has yielded the
unmistakable bones of an albatross, _Diomedea_.
Most Pleistocene birds are generically, even specifically, identical
with recent forms; some, however, have become extinct, or they have
become exterminated by man. A great number of birds' bones have been
found in caves, and among them some bearing marks of human workmanship.
In France we have a large and extinct crane, _Grus primigenia_, but more
interesting are the numerous relics of two species, the concomitants
even now of the reindeer, which were abundant in that country at the
period when this beast flourished there, and have followed it in its
northward retreat. These are the snowy owl, _Nyctea scandiaca_, and the
willow-grouse, _Lagopus albus_. A gigantic swan, _Cygnus falconeri_, is
known from the Zebug cavern in Malta. From caves of Minas Geraes in
Brazil, O. Winge has determined at least 126 species, of which nearly
all still survive in the country. Kitchen-middens of England, Ireland
and Denmark reveal the existence of the capercally, _Tetrao urogallus_,
and of the great auk or gare-fowl, _Alca impennis_; both species long
since vanished from those countries. In the fens of East Anglia have
been found two humeri, one of them immature, of a true _Pelecanus_, a
bird now no longer inhabiting middle Europe.
Until a very recent epoch there flourished in Madagascar huge birds
referable to the Ratitae, e.g. _Aepyornis maximus_, which laid enormous
eggs, and not unnaturally recalls the mythical "roc" that figures so
largely in Arabian tales. New Zealand has also yielded many flightless
birds, notably the numerous species and genera of _Dinornithidae_, some
of which survived into the 19th century (see MOA); _Pseudapteryx_ allied
to the _Kiwi; Cnemiornis_, a big, flightless goose; _Aptornis_ and
_Notornis_, flightless rails; and _Harpagornis_, a truly gigantic bird
of prey with tremendous wings and talons.
[Illustration: FIG. 19.--Extinct Crested Parrot of Mauritius
(_Lophopsittacus mauritianus_).
From a tracing by M.A. Milne-Edwards of the original drawing in a MS.
Journal kept during Wolphart Harmanszoon's voyage to Mauritius (A.D.
1601-1602), _penes_ H. Schlegel (_Proc. Zool. Soc._ 1875, p. 350).
Reduced.]
It is, of course, quite impossible, in a survey of extinct birds, to
divide them into those which are _bona fide_ fossil, sub-fossil,
recently extirpated and partially exterminated. Nor is it possible,
except in a few cases, to decide whether they have come to an end
through the agency of man or through so-called natural causes. Like
other creatures birds have come, some to flourish and stay, others to
die out.
[Illustration: FIG. 20.--Mandible of _Aphanapteryx_, side view. (From
the original in the Museum of Zoology of the University of Cambridge.)]
Mauritius is famous for the dodo, killed off by man; there was also a
curiously crested parrot, _Lophopsittacus_ (fig. 19). In the Mare aux
Songes have been found the bones of another parrot, of ducks, pigeons,
rails, herons, geese and of a dwarf darter, _Plotus nanus_, all
sub-fossil, now extinct. Very interesting is _Aphanapteryx_ (fig. 20), a
long-billed, flightless rail, practically the same as _Erythromachus_ of
Rodriguez and _Diaphorapteryx_ of Chatham Island. Reunion possessed the
peculiar starling, _Fregilupus_. Rodriguez was inhabited by _Pezophaps_,
the solitaire, _Necropsittacus_ and _Palaeornis exsul_, which is now
probably extinct. The Antilles tell a similar tale. The great auk, once
common on the British coasts, those of Denmark, the east coast of North
America, then restricted to those of Newfoundland, Greenland and
Iceland, has been killed by man, and the same fate has overtaken the
Labrador duck, the Phillip Island parrot, _Nestor productus_, and the
large cormorant of Bering Island, _Phalacrocorax perspicillatus_; and
how long will the flightless cormorant, _Ph. harrisi_ of the Galapagos,
survive its quite recent discovery?
[Illustration: FIG. 2l.--Pied Duck (_Somateria labradora_), male and
female. (From specimens in the British Museum. Reduced.) ]
AUTHORITIES.--A. Milne-Edwards, _Recherches anatomiques et
paleontologiques pour servir a l'histoire des oiseaux fossiles de la
France_ (Paris, 1867-1868); F.P. Moreno and A. Mercerat, _Catalogo de
los Pajaros fosiles de la Republica Argentina. Anales Mus. La Plata_,
1891, 21 pls.; O.C. Marsh, _Odontornithes: A monograph of the Extinct
Toothed Birds of North America_ (New Haven, Conn., 1880); R. Lydekker,
article "Fossil Birds," in A. Newton's _Dictionary of Birds_ (London,
1893); Cat. Foss. Birds, Brit. Museum, 1891; K. v. Zittel, _Handbuch
der Palaontologie_, i. 3 (1887-1890); C.W. Andrews, "On the Extinct
Birds of Patagonia," _Tr. Zool. Soc_. xv., 1899, pp. 55-86, pls.
14-17.