Paleontological Institute of the Russian Academy of Sciences
For about twenty years the authors have studied terrestrial tetrapod material and, using some
simple methods, have produced a series of zoogeographical reconstructions from Carboniferous to
Some of these results have been published in Russian and we believe that it may be useful
to produce a summary of this work in English.
Some of our results look very unusual, and we thought so at the beginning as well,
but our reconstructions are not imagination.
They are projections of terrestrial tetrapod systematics on to geography (see materials and
methods). And, if our reconstructions are wrong, it means that something is wrong with tetrapod
This does not mean, of course, that all of our results are precise.
Some of them can be and must be corrected. But, following A.R.Wallace,
we have studied all the land masses of the Earth and used all available material.
We have received some new results and we may begin to correct them now.
Approximately 1% of mammals "disagree" with our reconstructions.
Some of them are discussed in "Some taxonomical results".
One of the most important aspects of this work is the method used,
as well as some conclusions conserning systematic position of particular groups
that can hardly be obtained by means of standard zoological methods.
The text was written by N.Kalandadze who accepts responsibility for any mistakes.
MATERIALS AND METHODS
We used data on the geographic and stratigraphic distribution of terrestrial tetrapods
(non-marine and non-flying). Each taxonomic group used was considered to be monophyletic,
monotypic and monochronous in origin. Faunas were compared by the degree of their taxonomic
isomorphic characters at the levels from family to genus inclusive.
At the first stage of the work, all faunas were compared with each other in pairs,
regardless of their present or past position on the Earth's surface.
In the analysis of each pair of faunas used two operations :
First, the operation of "falling through" : if a certain taxon showed direct linkage between two
faunas (occured in both faunas at a certain geological time stage), but this linkage could be
explained by the presence of the taxa in the faunas of the previous time, we excluded such taxa
from the consideration concerning the zoogeography of the later time stage.
Second, the operation of reduction : if a direct linkage between the faunas of two regions turned
out to be weak and could be completely reduced to the connection between the two faunas
through a third (or more) fauna (that is, each taxon of the direct linkage corresponds to the same
taxon of the indirect linkage),such a linkage was considered to be false, Reduceable to a set
of other linkage (for additional details of the methods see : Kalandadze, Rautian, 1980-1991.
RESULTS AND DISCUSSION
Fossils of Late Devonian tetrapods are known from different territories (Greenland, Russia,
Australia); but their scarcity makes them unsuitable for a reliable zoogeographical investigation.
We tried to use sarcopterygian and dipnoan data, but obtained no satisfactory results; perhaps
owing to that these fishes were not strictly freshwater.
Two well-known Carboniferous terrestrial tetrapod faunas of North America, and Western and
Central Europe are so similar that it is possible to consider them as two parts of the same fauna.
This fact is well known and was confirmed in our analyses (Kalandadze,Rautian,1981).
High levels of endemism shows that in the Early Permian,
three were three different faunas on three separate land masses:
1. North America + northern part of Eastern Europe.
The most abundant amphibians were Lepospondyli and archaic Labyrinthodonts : Edopida and
Eryopida. Some large amphibians show good adaptation to life away from water. They had a
heavily ossified robust skeletons, with no trace of lateral lines on the skull and lower jaw. As these
kinds of amphibians are known since the Late Carboniferous, we may say, that in the Late
Carboniferous and Early Permian some amphibians tried to "organize" a good terrestrial biota
before the reptiles.
Since the Middle Carboniferous, we know of some groups of reptiles (Cotylosauria, Diapsida,
Theromorpha) had been able to oust amphibians from their ecological niches; thus, we know why,
since Late Permian, most amphibians have become freshwater animals.
The most common terrestrial animals in North America were Pelycosauria, not Therapsida.
Some years ago a few fragments of theromorphs were identified as therapsids.
Based on the historico-zoogeographical data, we suggested that all these fragments
should belong to sphenacodont pelycosaurs (Kalandadze, Rautian,1983)
and Robert Reisz agreed with us (pers.comm.).
At this time we know of no Early Triassic reptiles, and few Middle Triassic reptiles in
North America, however we believe that no therapsids will be found in North America
until the Late Triassic, when all continents were joined and therapsids and primitive mammals
entered North America.
We do not know about any confirmed parareptiles in North America,
but R.Reisz believes that Acleistorhinus is related to Lanthanosuchia.
If this is true, Acleistorhinus is the first known parareptile from North America.
2. West Europe + Middle Asia + China.
The most common labyrinthodonts were the Archegosauroidea and small unusual amphibians,
Discosauriscidae. We follow M.Ivachnenko's suggestion that discosauriscids are amphibian
ancestors of Parareptiles. That separate stock of reptiles - Parareptilia - M.Ivachnenko (after
E.C.alson) traced from Discosauriscidae to Pareiasauria, Procolophonia and Chelonia
3. South America + Africa + ?.
We know only a few taxa from these territories. But the known genus Mesosaurus, whose
skeletons are abundant in West Africa and Brazil, confirms that these continents were joined in
Early Permian. We do not know of any good Early Permian fossil tetrapods from India and
LATE PERMIAN - MIDDLE TRIASSIC
At the beginning of the Late Permian and Early Triassic other parts of Laurasia
(Scotland, Russia and China) were connected with Gondwana.
Previous investigations have shown that the major zoogeographical patterns were the same from
Late Permian to Middle Triassic, when North America and some parts of Western and Central
Europe were isolated.
The faunas of these territories contain some archaic elements; parts of ancient groups.
The differences between these two faunas are not substantial and we believe that they belong to
different provinces of the same Laurasian zoogeographical region.
Some groups of primitive amphibians and captorhinomorphs are known from that region,
especially in North America.
And in all cases both of these faunas show essential differences from the fauna of Gondwana.
Since all other faunas show a high level of similarity, we suppose that all these faunas belong to the
Gondwana zoogeographical region. South America, Africa, India, Antarctica and Australia were
joined at that time, and all the faunas known from those territories were very similar.
The situation with northern faunas is not so clear.
The well-known Scottish Late Permian fauna (from Elgin) includes
only three genera: Geikia, Gordonia (Anomodontia) and Elginia (Pareiasauria).Anomodontia
and Pareiasauria are typical of Gondwana, not Laurasia (Kalandadze, Rautian, 1981).
After the discovering by V.P.Amalitzky the Northern Dvina Faunal Assemblage with large
pareiasaurs, gorgonopsians, therocephals and dicynodonts, the relationships of these faunas with
Gondwanian faunas has become obvious.
Now we can say that large northern continental masses from Scotland to China were joined at that
time. And some provincial differences between these northern faunas and southern faunas confirm
our conclusion that from the Late Permian up to the Middle Triassic the northern continents
adjoined Gondwana at least twice: at the beginning of the Late Permian (Ecca zone or earlier) and
at the beginning of the Early Triassic (Lystrosaurus zone).
The most common animals of the Gondwanian zoogeographical region were Parareptilia
(Pareiasauria and Procolophonia),
Therapsida and freshwater Labyrinthodontia.
One very important group of animals "disagree" with our reconstruction, these are some of the
Triassic Labyrinthodontia. At the beginning of Triassic in Western Europe, (since the Late Permian)
some Gondwana-type labyrinthodonts appeared suddenly on the isolated land masses. In Fig. 2 a,
2b the arrows show the moment of changing amphibian faunas in North America and in Western
and Central Europe. These groups of labyrinthodonts were to have a single peak in both parts of
the Gondwanian zoogeographical region: in the south and in the north.
And that is the reason for North America and Western Europe to display two peaks of
labyrinthodonts. Gondwana and Eastern Europe had one peak of labyrinthodonts
As no therapsids appear in North America and Western Europe before the Late Triassic (except
for Procynosuchus sp., from Germany), we examined these labyrinthodonts more carefully and
revealed that all of them had belonged to the families with representatives having been found in the
marine deposits. These families are the Capitosauridae, Benthosuchidae, Trematosauridae and
We may suggest that, at the beginning of the Triassic, some labyrinthodonts tried to enter salt
marine water (and could cross marine straits). But at the beginning of the Triassic, Ichthyopterygia,
Sauropterygia and Placodontia are known to emerge. This can explain, why after the Late Triassic
one finds only a snall number of fossil Jurassic and Early Cretaceous labyrinthodonts in China,
Mongolia, Middle Asia and Australia. Probably they were ousted by the reptiles.
In the Late Permian, we know one very important change in terrestrial biota. In the beginning of
the Late Permian,there was unique the Ocher Faunal Assemblage (Perm Region, Russia).
All terrestrial animals in this Assemblage were therapsids: small and large, carnivorous and
Later, in the Northern Dvina Assemblage, all the carnivores were therapsids (gorgonopsians,
therocephals). But the herbivorous animals belong to two groups : dicynodonts (Therapsida) and
pareiasaurs (Parareptilia). Large forms of herbivorous therapsids had died out.
In the terminal Late Permian fauna of Russia (Vjasniky = Daptocephalus zone) there were two
large carnivores: a new Whaitsid therocephal and the first archosaur (Archosaurus). This was a
very important moment in the history of terrestrial tetrapods: large carnivorous therapsids were
being replaced by Archosauria.
Since that time, Theromorpha (and, later, Mammalia) evolved "in the shadow of archosaurs".
It was one of the most important moments in the whole mammalian history.
"The first two-thirds of mammalian history" were spent "in the shadow of dinosaurs" (Lillegraven,
Kielan-Jaworowska, Clemens, 1979).
From then until the Late Triassic we know very few large theromorphs, all belonging to
Dicynodonts. However, small therapsids survived until the Paleocene (Chronoperates in North
America). Having originated from therapsida and being suppressed by dinosaurs in large-size class,
all Mesozoic mammals were small-sized.
The time of maximal regression, a zoogeographical Pangaea : when all continents were joined
and North Africa was the centre of the world. This was the time when Chelonia, Crocodylia,
Dinosauria, Pterosauria and Mammalia began to evolve.
Some provincial differences in faunas show that recent oceans began to open by the Late Triassic.
We performed a special study of the Late Triassic using Thecodontia, Dinosauria, Theromorpha
and Mammalia only (Kalandadze, Rautian,1991).
All traces of the previous zoogeography divisions disappeared in Late Triassic Pangaea.
Thus, the Late Triassic is the most ancient time whose historical zoogeography can be
reconstructed with the use of recent materials.
EARLY - MIDDLE JURASSIC
The largest catastrophe of terrestrial biota from the Devonian up to
Recent occured (Kalandadze, Rautian, 1983-1993; Benton, 1985-1989).
This is the reason it is impossible for us to make a reconstruction for this time using our methods
(the materials from all other periods in the history of terrestrial tetrapods from Carboniferous up to
Recent appeared aviable for our reconstructions). Though terrestrial tetrapods were found
everywhere; North America, Europe, Asia, Africa, Madagascar(in Australia, the volume of
material is too small).
Special articles concerning this subject were published (Kalandadze, Rautian, 1993 a, 1993 b).
Many high level taxa became extinct and many high level taxa appeared near the boundary
between the Early and Middle Jurassic; near and during Early and Middle Jurassic.
Some of these taxa are :
Lepospondyli - Apoda
Batrachomorpha - Salientia
Batrachosauria - Chelonia
Eolacertilia - Lacertilia
Thecodontia - Crocodylia
Synapsida - Mamamlia
Dinosauria and Pterosauria are the only two unsuccessful members of this taxa.
Thus, we may say that the Late Jurassic was the time when the Recent biota began to evolve.
The only but very important difference between the Late Jurassic and Late Triassic
reconstructions is the separation of North America and South America.
It means the Southern and Northern continents were separated.
From that time we know of some groups of mammals : Kuehneotheriidae, Amphidontidae,
Amphitheriidae, Peramuridae (see Table 1).
All of these mammals belong to archaic therians, but not Metatheria and Eutheria.
The oldest fossils of Metatheria and Eutheria are known from the end of the Early Cretaceous
(Aptian-Albian). But in the collection of Paleontological Institute Russian Academy of Science
there are some teeth of Zalambdalestidae and Deltatheridiidae (Reshetov V.J., pers. comm.),
collected in Mongolia (Psittacosaurus zone). All the mammalian fossils were published as "Aptian
- Albian stage"; however, the Psittacosaurus fauna is usually believed to be the Neocomian.
Then, Alex Agadjanian, examining published material from Gumiarotta (Late Jurassic of Portugal)
found that Crusafontia and Henckelotherium resemble Amblypoda and may belong to this order.
In any case we may suggest that the Late Jurassic was the time of separation of Southern and
Northern continents and should be the beginning of divergent evolution of Metatheria (on the
South) and Eutheria (on the North).
LATE JURASSIC - EARLY CRETACEOUS
Some mammalian materials are known from North America, Europe and Africa.
It is important to note here that in the Late Jurassic we know a Multituberculata fauna from North
America (Morrison formation). All that Multituberculat