John Elihu Hall.

The American journal of science online

. (page 41 of 61)
Online LibraryJohn Elihu HallThe American journal of science → online text (page 41 of 61)
Font size
QR-code for this ebook


conclusion that the "dominant red color of the whole of the Tri-
assic formation, considered in connection with its feldspathic
sandstones, indicative of the kind of erosion, mud-cracked shales,
disseminated gypsum, and calcite, indicative of conditions of
sedimentation, point ... to a subarid climate," and further-
more that "the Triassic conglomerates . . . are associated with
many features of climatic significance . . . which independently
indicate a semiarid climate with hot summers and possibly cold
winters " (p. 259).

Fenner (1908, p. 305), in describing the shales of the New
Jersey Newark areas, summarized the physical phenomena
thus :

"They are finely comminuted siliceous material, strongly im-
pregnated with oxide of iron. Their laminations may be
paper-like in thinness, but are generally coarser. On exposure
to the weather they break up into a multitude of crumbly
fragments. Mica scales are very plentiful. The surfaces of
the laminae frequently show a multitude of irregular markings
— grooves, pits, curved lines, lumps, smooth patches of
irregular shape, etc., not all of which can be decipliered with
any certainty. Many, however, can be identified. Mud-
cracks, rain-pits, and worm-grooves are frequent. Rill-marks
are sometimes found. At times films of impalpable sediment
are found in the depressions in the lumpy surfaces of certain
sandstone layers, which, in their delicate markings, suggest
irresistibly the frothy scum left in hollows after a rain."



Digitized by VjOOQ IC



li, S. Lull — Zife of the Connecticut Trias. 403

One very characteristic plivsical phenomenon impressed
upon the sandstones and shales of the Connecticut valley is
that of mud-cracking as the fresh deposits dried under the
ardent heat of the Tnassic sun. These cracks are often found
associated with the fossil footprints, and in many instances,
notably from the Portland, Connecticut, sandstone quarries,
they lie in the axes of the digital impressions, often radiating
from the tips of the toes, thus showing conclusively that the
drying was subsequent to the passage of the animal, the cracks
following the already weakened lines of least resistance.

Yet another very characteristic Connecticut valley phenom-
enon is that to which the elder Hitchcock gave the poetic
name of "Nature's Hierogly'phics." As he says, the most
remarkable locality is at the JPortland quarries, "where some-
times the surface looks like mosaic, or rather like a pavement
of polygonal masses, with mortar between the pieces." Bar-
rell describes this as "mud-cracks filled with seolian sands."
He says (pp. 279-80) :—

"Silt and sand will be blown over and fill up the cracks
developed by the drying of argillaceous water-laid deposits.
Consequently, the sand is filled in under the raised rims of the
polygonal discs and becomes continuous with the mantle of
sand above. In this way the concavity upward of the indi-
vidual plates is preserved and the mud-cracks are not
obliterated, even in a silty clay which would crack and
crumble immediately upon being rewet by the advancing
waters of the following inundation. Experiments by the
writer [Barrell] go to show that the upturned edges of the
clay plates would not usually hold their form while the broad
sweep of sand-laden waters should deposit clean sand both
under the edges and over the plates. The concavity of the
plates thus testifies to seolian burial and such may be distin-
guished from mud-cracked flats buried by fluvial action."

Other phenomena indicative of climatic conditions are the
impressions of frequent hard showers, such as are often
observed in semi-aria regions, and pieces of recent sun-cracked
mud deeply pitted with rain impressions secured by Professor
Marsh on the Laramie plains in 1868 might well be of Triassic
origin.

Still other phenomena, namely the impressions found in
Portland and attributed to a fucoid to which was given the
name of Dendrophycua triassicus by Newberry (1888, p. 82),
have been seen in actual formation upon the clav banks of
streams, and are nothing less than the wonderfully wrought-
out series of brandling rill marks made by tiny streams of
trickling water.

The animals of the Connecticut Trias, in so far as they



Digitized by VjOOQ IC



404 R. S, LuU — Life of the Connecticut Trias.

throw light upon past climatic conditions, inclade the remains
of at least two species of shells, both belonging to the fresh-
water TJnionidse, which preclude the possibility of saline tidal
waters, at least in the neighborhood of Wilt)raham, Massa-
chusetts, a locality which, unfortunately for the estuarine theory
of origin, is far to the south of places where the sediment
would seem to demand the strongest tides. On the other
hand, the presence of shells implies more or less permanent
waters, either in slow moving or impounded condition. The
one insect reported from the valley is found in great abund-
ance at Turners Falls, Massachusetts, and has been described
as the aquatic larva of a neuropterous insect, hence again
implying the presence of waters of some duration. If the
period of larval life was equivalent to that of the ephemerids
of to-day, the water must nave continued not one season but
three; this may, however, have been an annual insect the
larval life of which would require but a transitory stream.
The invertebrate trails show no characters which would debar
them from such a climatic environment as Barrell has assumed
for the Connecticut Triassic.

Fishes are, with the exception of one crossopterygian, all
ganoids. And, while confined stratigraphically to two or three
black shale bands, their geographical range is from Turners
Fails to New Haven. They are, however, all of fresh-water
aflBnities, and may well represent the recurrence of climatic
cycles of greater than average humidity and consequent expan-
sion of the aquatic habitat, or a disturbance of the drainage,
due to volcanic damming or deformation, the climatic condi-
tions remaining constant.

Over the terrestrial vertebrates, aside from a few of the
forms unquestionably dinosaurian, so deep a shadow of obscur-
ity rests that safe conclusions may hardly be drawn. There is
no reason to suppose that all are reptilian; and, if the Amphibia
of that day were of similar constitution to the present-day
descendants, to whom a one per cent solution of salt is fatal, the
proof of their presence would preclude the possibility of
marine waters, and add their evidence in favor of continental
deposition to that of the lower forms. Tliere are, however,
stegocephalians known from brackish water deposits.

On the Laramie plains in 1899, when conditions were dry
even for a semi-arid climate, I found in the dust of the ground
within the tent a large and lively salamander of brilliant color-
ing whose advent and departure were alike mysterious. Van
Dyke in his description of the desert remarks that all desert
trails run in straight lines, showing the animal to be not prowl-
ing but intent in getting across to the mountain. The same is
tme of the fossil trails of the Connecticut valley ; and from the



Digitized by VjOOQ IC



R, S. ZtUl — Life of the Connecticut Trias. 405

compact type of foot, loug stride, sometimes suddenly lengthen-
ing marvellonsly, and the narrow trackway of many species, it
can easily be seen that the character imposed by the desert of
speed and great travelling powers was here at a high premium.
As I have shown elsewhere (1910, p. 37), a climate of semi-
aridity, compelling cursorial adaptation as a means of getting
food but more especially water, may well have been an impel-
ling cause in dinosaurian evolution. Bipedality among lizards
of to-day is, so far as I am aware, confined to denizens of semi-
desert environment, certain instances being the large frilled
lizard, Chlamydosaurus (Sayville Kent), of Australia, and
several lacertilian species of our own Southwest.

That water was rare and at a premium when the rains did
come is evidenced by the frequency of the association of rain-
prints with dinosaurian tracks and the above-mentioned mud-
cracks which followed the passage of the animal. Again, the
depth of the impression of the tracks of two species of animals
upon the same strata is sometimes entirely out of proportion to
the apparent difference in the makers' size, for the presump-
tion IS that then as now the supporting area of an animars
feet must have borne a certain ratio to the weight in accord-
ance with the type of environment to which the creature was
adapted. The inference is, therefore, that the passage of the
two animals W6W on their way to or from a water hole during a
period of desiccation, and that the deeper impression was made
some time before the shallower one and nearer the time of the
preceding rains.

TTie Vegetal Environment,

Chamberlin and Salisbury (Vol. iii, pp. 38-40) speak thus
of the plant life of the Triassic:

"The record of the vegetation is very imperfect. The
vegetation was probably scanty in reality, for . . . arid
tracts imply conditions inhospitable to plant life. An environ-
ment that could give rise so generally to coarse red sandstones
and conglomerates — even limestone conglomerates — could not
well be congenial to luxuriant vegetation.

" The Triassic was distinctly an age of gymnosperms the
world over ; the supremacy of the pteridophytes had ceased,
though ferns, true to their persistent nature, still held an
important place, and the equisetales were a more vital factor
than now. . . . conifers of the types that had come in dur-
ing the Permian, and kindred new ones, were prominent,
while the cycadean group was still in a stage of deployment
and occupied the central place of interest. . . . The Triassic
conifers bore the scrawny aspect of the walchias and voltzias
of the Permian. ... It does not appear from the record that

AM. Jour. Sci.— Fourth Series, Vol. XXXIII, No. 197.— May, 1912.
27



Digitized by VjOOQ IC



406 a. S. LvU — Life of the Connecticut Trias.

any of these gyranoeperms were especially large, but on the
contrary rather dwarnsh, the conifers bearing the aspects now
found on sandy barrens and arid tracts. The calamites liad
given place to true equiseta, which were represented by forms
that were gigantic in comparison with modern types. . . .

" In the closing stages of the period, the Khsetic epoch and
its equivalents, there seems to have been much amelioration of
the previous hostile conditions and a much ampler develop-
ment of the flora. The larger part of the known American
fossils belong to this stage. In favored portions of the Newark
series from Connecticut to North Carolina, plant remains
occur, and in the coal-beds of the latter state and of Virginia,
the flora is more amply represented."

The Fauna.

In both vertebrate and invertebrate relics the proportion of
known fossils to footprints is much the same, the former being
of such extreme rarity as to warrant special mention of practi-
cally every find.

Invertebrates.

Of the actual fossils the species represented are but four, —
two known species of molluscs, a small phyllopod crustacean,
Estheria sp., and a single insect species of which fortunately
there are numerous examples, all, however, from three or four
localities in the neighborhood of Turners Falls, Mass., and
near Middletown, Conn., though whether the latter locality
yields the same form as that at Turners Falls is unknown.

A brief summary of the invertebrate species follows :

Of the phylum Arthropoda the Class Hexapoda is repre-
sented by tlie one known species Mormohicoiaea articulatus
Hitchcock. This creature was first described by Hitchcock in
1858 as a crustacean and its true relationships were discovered
by J. D. Dana, to whom Hitchcock sent specimens for examin-
ation. Dana, in a postscript to his letter reporting on the
insect, says : " The larve was probably the larve of a neuropter-
ous insect, which often has false legs along the abdomen ; but,
if so, it is surprising that there are no legs to the corselet,
neuropterous larves having three pairs." This. insect was
afterwards studied by Scudder, who published an elaborate
monograph amplifying the previous descriptions. It remained,
however, for the present writer to have the good fortune to
find upon a single individual among many impressed upon the
shale, well-preserved remains of the antennae and limbs which
served still further to verify the taxonomic conclusions of
Dana. These are described in detail in the meinoir from
which this extract is made. The further placing of this insect



Digitized by VjOOQ IC



M. S, Lull — Life of the Connecticut Trias. 407

in the classificatory scheme brings it into the order Neu-
roptera, family SialidflB.

A second arthropod has just been announced (Jan. 1912) by
Miss Mignon Talbot, professor of geology in Mount Holyoke
College, and represents in all probability a new species of the
phyllopod genus Estheria^ heretofore reported from the New
Jersey-Pennsylvania area but not from tne Connecticut valley.
The locality is West Holyoke, Massachusetts, which would
place it geologically in the " Lower Series of granitic, coarse
sandstones," exactly what one would be led to expect from the
distribution of the genus in the New Jersey-Pennsylvania area.

MoUusca have been reported several times from the Con-
necticut valley, but the only authentic find seems to be that
recorded by Emerson (1900, p. 58). This slab, which has
been sent to me for study, is from near Wilbraham, Massa-
chusetts, and contains at least 14 imperfect impressions repre-
senting at least 2 species of undouoted dnio^ the type of
Emerson's species being similar to U. alatus. It should here-
after be known as Umo wilbrahamenais. The second species
is quite distinct from the first but is too imperfect to character-
ize. It is also unquestionably Unio^ and may hereafter be
known as U. emersoni in honor of Professor Emerson. Ano-
plophora^ the genus to which Emerson referred the first species,
Schuchert says is probably always marine, and the shells in
question are doubtless in fresh-water deposits. The slab, which
is a portion of an ice-transported bowlder, the parent ledge of
which is probably unknown and therefore not necessarily as
far south in the valley as Wilbraham, gives evidence of having
been deposited in permanent waters, a habitat in keeping with
that of present-day Unios. Wilbraham being toward the east-
ern side of the valley, is, therefore, near the summit of the
Newark series stratigraphically.

Invertebrate Trails.

A summary of the invertebrate trails given by Professor C.
H. Hitchcock in 1889 is as follows :

Hexapod Arthropoda, 8 genera and 24 species.

Inferior Arthropoda, including larval forms and worms, 10
genera, 16 species.

MoUusca, 4 genera and 6 species.

Incertce sedis, 5 genera, 6 species. '

This places the total number of invertebrate and questionable
trails at 52. In view of the number of undoubted vertebrate
species known from the Newark system and the teeming num-
ber of living invertebrates, especially arthropods, compared
with vertebrates, even under adverse climatic conditions, this



Digitized by VjOOQ IC



408 R, S. LuU — L^fe of the Connecticut Trias.

number does not seem excessive. In fact, I imagine it may
fall far short of the number of continental invertebrates of
Newark time. My own grouping modified from that of
Hitchcock (1889) is as follows :

Phylum Arthropoda
Class Insecta

Genera Acanthichnus with 9 species; Bifurculapes with
5 si)ecie8 ; Lithographua with 3 species ; Gopeza with one
species ; HexapodicTmua with 2 species ; Conopsoides with 2
species; Ha/rpepus with one species; Sagittarius with one
species.

Class Incertse sedis

Genera Lumda^ one species ; Pterichnus^ 2 species ; Ham-
ipes^ one species; SpJuBrapus^ 2 species; Grammepus^ 2
species ; Stratipes^ one species ; Saltatory 2 species.

Phylum Vermes

The old term Vermes is used as being more non-committal
than Annelida, as one cannot be sure that in every case the
following track-makers were oligochete annelids, though doubt-
less some were.

Genera Herpystezoum with 4 species; HaLysichnus^ 2
species; Cunicularius^ one species; Cocfdea^ one species;
Vochlichnus^ one species.

Phylum Mollusca ?

Under this head are placed some peculiar multiple trails, the
duplication of which seems to debar them from the worms.
Genera Bisulcm^ one species ; TrisvZcus^ one species.

Genera of doubtful origin and character.

Genera Harpagopus^ one species; Orammichnus^ one
species ; Climacoaichnus^ one species ; ^nigmichnus^ one
species.

The Aquatic Vertebrates. ~"^^

Among the vertebrate fossils found in the Newari^'wsks of
the Connecticut valley, two classes, fishes and reptiles, ar^yrep-
resented by actual osseous remains ; the latter surely, and prob-
ably the Amphibia, are recorded by their footprints!^ WhetliV
or not the two higher classes, the birds and mammals, are rep-
resented is not yet proven, though mammalian remains ar^
known from the Newark system in North Carolina and thp



1

Digitized by VjOOQ IC



B. S. Lull — Life of the Connecticut Trias, 409

first authentic avian relics, those of ArcJuBopteryx^ already a
long way along the road to avian perfection, coming as it does
from the Middle Jurassic, would surely imply birds in some
stage of their evolution during Newark time.

Professor C. R. Eastman, in a characteristically excellent
paper (1911, p. 28), gives the following summary :

" List of Fossil Fishes occurring in the ^ Newark' or Upper
Triassic Rocks of Eastern North America. [In this list the
names of those species occurring in the Connecticut valley are
denoted by an asterisk.]

Crossopterygii

Family Coelacantbidae

1. *Dipluru8 longicaudatua Newberry

Actinopterygii
Family CatopteridsB

2. * Catopterua gracilis J. H. Red field

3. * Catopterua redfieldi Egerton

4. Dictyopyge macrura (W. C. Redfield)

Family Semionotidaa

5. *Acentrophorus chicopensis 'Newherry

6. *Semionotu8 agassizi (W. C. Redfield)

7. Semionotus brauni (Newberry)

8. Semionotus eltgans (Newberry)

9. * /Semionotus fulttis (Agassiz)

10. Semionotus gigas (Newberry)

11. Semionotus lineatus (Newberry)

12. * Semionotus micropterus (Newberry)

13. * Semionotus ovatus (W. C. Redfield)

14. Semionotus robustus (Newberry)

15. ^Semionotus tenuiceps (Agassiz)

Family Eugnatbida)

16. *Ptycholepis marshi Newberry,"

This fauna, except for one crossopterygian, is made up exclu-
sively of ganoids and, judging by comparisons made with fish
faunas of the Old World, is considered to be " of more or less
manifold nature, and corresponds in a general way to the inter-
val between the uppermost Muschelkalk and the basal division
of the Keuper in the Mediterranean region."

The fish remains are nearly all from the two general levels
of black bituminous shale, which also contain the plant relics,
in varying profusion. Rarely are footprints found in juxta-
position to the fishes and never, so far as I am aware, upon the



Digitized by VjOOQ IC



410 R. S. Lvll — Life of the Connecticut Trids.

fish-bearing shales themselves. Geologically, the shale bands
are associated' with the trap outflows, an anterior bed following
immediately upon the anterior trap sheet to a thickness of from
50 to 100 feet and a posterior zone of about 100 feet imme-
diately preceding the posterior trap, the relationship of the
shale and trap being in one case the reverse of the other.
Geographically, the fish localities are distributed from Turners
Falls, Massachusetts, to Lake Saltonstall, New Haven, Con-
necticut.

The Terrestrial Vertebrates.

Eeference has already been made to the great disparity in
numbers of actual bone remains as compared with the foot-
prints, and while the number of the latter contained in our
museums is so great as to be unrecorded, and many more have
been destroyed, the skeletal remains are by no means as rare as
is generally supposed, for as a matter of fact no fewer than
three genera and five species of dinosaurs, one of a belodon,
and two species of aetosaurs have been described from the
Connecticut valley area alone, while the actual number of
specimens naturally exceeds this record of forms. Geograph-
ically, osseous remains are reported from Greenfield, Belcher-
town, South Hadley, and Springfield, Massachusetts ; and from
East Windsor, Ellington, Manchester, New Haven and Sims-
bury in Connecticut. The footprints occur scatteringly the
entire length of the valley fronj above Turners Falls to New
Haven, but the greatest abundance both of separate localities
and profusion of species and specimens is in the more northern
portion of the area, specifically around Turners Falls and near
South Hadley, Massachusetts. Hitchcock, in the "Ichnology
of Massachusetts," enumerates no fewer than 38 quarries for
fossil footprints, and a very few localities have been discovei-ed
since that time. The geological sequence of the various fossil
and footprint localities is shown in the appended table.

The creatures known from the bones are as follows : —

Class Reptilia
Order Parasuchia Huxley

Suborder Aetosauria Nicholson and Lydekker (=Pseudo8uchia
Zittel)

Family A^tosanridae

Stegornus arcuatus Marsh

From the lower series of granitic, coarse sandstones (Fair
Haven arkose). New Haven, Conn.



Digitized by VjOOQ IC



a, S. Lull — Life of the Connecticut Trias. 411

Stegomus longipes Emerson and Loomis

From the upper series of sandstones (Longmeadow sand-
stone), Longmeadow, Mass.

Suborder Phytosauria Baur

Family Pbytosanridae McGregor

Mhytidodon ( Belodon) validtM Marsh

From the lower series of granitic, coarse sandstones, of
Simsbury, Conn.

Order Dinosauria Owen

Suborder Theropoda Marsh (Carnivorous Dinosanra)

Superfamily Megalosauria Baur

Family Anchisauridae Marsh

Anchisaurus {Megadactylua) polyzelus (E. Hitchcock, Jr.)

From the upper series of sandstones and shales (Longmeadow
sandstone), Springfield, Mass.

Anchisauriis colarua Marsh

From the upper series, Manchester and East Windsor, Conn.

Anchisaurua solus Marsh

From the upper series of Manchester.



Ammosaurus mqjor Marsh
From the upper series of Manchester.



Superfamily Compsognatha Huxley
PodohesavruB holyokenais Talbot

From the upper series (Longmeadow sandstone). South
Hadley, Mass.

These forms may be briefly described as follows : —
The Parasuchia were reptiles, more or less lizard-like in
form with an outer armor consisting of bony plates which are
in part segmentally arranged. They were distinguished from
the later crocodiles mainly by the position of the internal nares
(nostrils), which were normal and not shifted to the rear by
the growth of a secondary bony palate. In the modern
crocodiles this is a device to prevent strangling while devour-
ing prey under water by bringing the nasal chamber in direct
communication with the glottis. The Parasuchia were both
aquatic, fish-eating forms and, in the aetosaurs, truly terrestrial
reptiles though still doubtless of carnivorous habits.



Digitized by VjOOQ IC



412 -/?. S. Lull — Life of the Connecticut Trias,

Stegomus arcuatus Marsh is represented by tfie impression
of the dorsal armor only, showinej it to have consisted of nar-
row transverse plates extending from the mid-line well across

Fig. 1.



Fig. 1. Restoration of Stegomus lonyipes Emerson and Loom is. About
two-sevenths natural size. Modeled by H. S. Lull.

the back, flanked by smaller plates along the sides, each series
overlapping its successor behind. The animal was estimated

Fig. 2.




Fig. 2. Anchisauriis colunts Marsh. Right side of the statuette showing
the flesh. One-tweuty- first natural size. Modeled by R. S. Lull.

by Professor Marsh to have been of " moderate size, prob-
ably eight or ten feet long." It is preserved in the Yale
University Museum.



Digitized by VjOOQ IC



B. S. Lull — Life of the Connecticut Trias, 413

Stegomtcs longipes Emerson and Loomis is much more com-
pletely known, as nearly the entire armor from neck to rump
is preserved as well as the skull, sacrum, and remains of the
limb-bones. The latter give indication of long slender legs,
the whole organism indicating an animal of small size with
limbs of such character as to indicate most strongly a correla-
tion with certain abundant footprints of the genus Batrachopus
in which the long step and narrow trackway indicate a mam-
mal-like gait though the feet themselves were still typically
reptilian. A restoration of Stegomus longipea is here shown



Online LibraryJohn Elihu HallThe American journal of science → online text (page 41 of 61)