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The American journal of science online

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74 Speyers —Heat of a Change in Connection with

Collecting for discussion, including the vaporization data, we
have







A


A'




140




+


44


1936


140-72= 68


176




+


79


6240


175 — 72=103


154




+


58


3364


164-72= 82


44


± 4





52


2704


44 + 72=116


50


± 4


— .


46


2116


50+72 = 122


125


± 8


+


29


841


125-72= 53


48


± 28


. —


48


2304


48 + 72 = 120


36


±





60


3600


36 + 72 = 108


82


± 6





14


196


82 + 72=154


76


±190





20


400


76 + 72=148


28


± 48





68


4624


28 + 72=100


60


± 4





36


1296


60 + 72=132


114


± 22


+


18


324


114-72= 42


145


±559


+


49


2401


145-72= 73


64


±211





32


1024


64 + 72=136


52


± 4





44


1936


52 + 72 = 124


67


■± 2





29


841


• 67 + 72=139


67


±299





29


841


67 + 72=139


86


± 1





60


3600


36 + 72=108


96


± 9


±








96 =96


100


± 9


+


4


16


100-72= 28


105


± 37


+


9


81


105-72= 33


51


±156





45


2025


51 + 72=123


67


± 3





29


841


67 + 72 = 139


98


±163


+


2


4


98 — 72= 26


97


± 9


+


1


1


97-72= 25


98


± 8


+


2


4


98-72:^ 26


202


± 49


+ 106


11204


202-72=130


22


± 17





74


6475


22 + 72= 94


34


± 46





62


3844


34 + 72=106


316


±240


+ 219


47950


315 — 72=243


312


±131


+ 216


40660


312-72=240


83


± 73





13


169


83 + 72=155


141


±147


+


45


2025


141 + 72= 69


—24


±150


— '


120


14400


-24 + 72= 48



96 = Mean 1 74287 = SA'.

The mean error of a single determination is therefore



/



34



and the mean error of tlie mean, 96, is

72

^ = 12.
V36



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Changes in Dielectric Constants and in Volumes. 75

The probable errors for single determinations and for the
mean determination are respectively

f72 = 48 and fl2 = 8.

At first inspection these figures are discouraging, but when
we find the mean error of a single determination to be 72
and then find that this mean error will more than bring
29 out of the 35 determinations into the mean of the whole,
namely 96, and that 5 of the 6 exceptions have experimental
errors of their own more than suflBlcient to bring them also
into the mean, and that the other one has an unknown experi-
mental error, the final result is not so bad and there is notninsr
to disprove the correctness of equation 4 and the constancy oi
the quotient e/Q. In other words, that the heat of a change
comes from a change in the field surrounding us and that this
change is measured by the dielectric constants of the compo-
nents of the system, is an assumption in agreement with the
foregoing experiments.

RntgerB CoUege, New Branswick, N. J.
Februaiy, 1908.



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76 W, C, Knight — Note% on the Genu% Baptanodon.



Art. VII. — Some Notes on the Genua Baptanodon^ with a
Description of a New Species ; by Wilbur C. Knight.

It was many years ago that Marsh described Baptanodon
(Sanranodon*), and with the exception of a very short paperf
by the same author in which he oescribes a new species, noth-
ing has been written to give us a better understanding of the
peculiar American Ichthyosaur until Charles Gilmore pub-
lished some additional and valuable information very recently
in Science.

Yet we do not know very much about this peculiar swim-
mer, and a great deal of information is desirable before it will
be possible to say with any certainty, whether there is any
great difference between Baptanodon and Opthalmosaurus or
not Several paleontologists have alraady expressed them-
selves in the belief that these genera are identical. For a
number of years specimens have been accumulating in the col-
lection of the University of Wyoming, and from these some
valuable points have been secured. From what I know of
Baptanodon I am in favor of retaining the name. In the fol-
lowing notes will be found some argument favoring this generic
name and showing how that Baptanodon differs from Opthal-
mosaurus.

Front Limb of Baptanodon. — Humerus about one-third
the length of the limb, with a stout twisted shaft that is greatly
compressed near the distal end. Planes passed through the
articulate ends of the humerus stand at an angle of 50°. The
head is slightly rounded and is almost identical with Ichthyo-
saurus. There are three distal facets; but they are not of
equal size. The facet for the ulna is the largest, the one for
the radius next in size, and the one opposite the pisiform is
rudimentary, for that bone was held in cartilage and did not
articulate with the humerus. These facets are elliptical in
form, and those opposite the ulna and radius elongated in the
plane of articulation in place of being vertical to it, as they are
in Opthalmosaurus. The radius is a subangular bone, with the
exterior margin reduced to a thin edge that is nearly straight.
It is also larger than the ulna, which is slightly hexagonal in
shape. The pisiform is subcircular in form and is the smallest
bone of the second segment of the limb. The next segment is
composed of four subcircular bones as noted by Marsh, but
the succeeding row is composed of only three bones. The
largest appears to have been formed by the consolidation of
three elements. This might have been considered as an indi-
♦ This Journal, xvii, 85. \ Ibid., xix, 169, 491.



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W. C. Knight — Notes on the Oenvs Baptanodon. 77

vidnal characteristic had I not found it in at least three ani-
mals. The limb that I have been stadying and have figured
differs from the one published by Marsh, inasmuch as the
abnormal number of digits do not appear until the phalanges
are reached, and then by a division oi the third digit. This
information has been secured from a specimen in the matrix
and is absolutely reliable. The carpals, metacarpals and pha-
langes are compressed grooved cylinders, the most of wnich
have slightly concave surfaces. The grooves are ornamented
with tuberosities for muscular attachment. Along the margins
of the limb the cylinders have their exterior borders reduced
to quite thin edges. Any one finding the limb of a Baptan-
odon for the first time scattered about in the field would surely




C




Figure 1. c. —Transverse section of an interior carpal ; d. — Terminal car-
pal ; B.— Marginal carpal. AU reduced one-half.

try to fit the ventral and dorsal surfaces of the metacarpals
together in trying to construct a digit.

In comparing the limbs of Opthalmosaurus and Baptanodon
one should consider the following points : In Baptanodon the
huraenis is about one-third the length of the arm ; it has a
twisted shaft which is greatly compressed. The distal facets
are all unequal in size and one of them is merely rudimentary,
besides they are elliptical in the plane of articulation. There
is also an abnormal number of digits, and the arm is much
more powerful and larger than found in Opthalmosaurus of
equal size. The indications are that Baptanodon was a remark-
able swimmer.

Rind Limb. — The hind limbs in the collection are too frag-
mentary to admit of accurate determinations. The femora
examined all have two facets only. I was not satisfied with



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78 W, C, Knight — Notes on the Oenus Baptanodon.



< «



Figure 2.— Right pectoral limb, dorsal aspect^ reduced about 2| times.



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W. C. Knight — Notes on the Genus Baptanodon. 79

the material in hand and wrote Dr. Beecher concerning the
material at Tale University, and he informed me that the ones
examined by him in the Yale collection had but two facets,
and that the humerii had three but one was very small. The
fact that Baptanodon so far as known has bat two elements
articulating with the femora is worthy of special consideration.
Vertebral Column. — The specimen S in the Wyoming col-
lection contains 41 precaudal vertebrse. These are consecutive
and represent the series from the head backwards. The atlas
and axis are so completely fused that there is not the slightest
trace of their union. Anteriorly the first vertebra (atlas and
axis) is only slightly excavated ; but upon this elongated verte-
bra there are two normal or almost normal processes* The
first vertebra (atlas and axis) is 41"^™ in length, and the second
is only 31™°* long. There is no intercentra between these (the
second and third) vertebrsB. It is also questionable whether there
is any between the atlas and axis and the axis and the basioci-
pital. If they are present they are so perfectly anchylosed to
the centra as to make it impossible to distinguish them. I
have only examined a single specimen, and while I think it
possible that all of the intercentra have disappeared, it will be
desirable to make further examinations before this point can
be passed upon. In specimen S the vertebrae gradually increase
in length and width from the atlas and axis to No. 19 ; the
third vertebra being SI""" long and 80°*™ wide and the nine-
teenth 41°»™ long and 90™™ wide. These are separated by
intercentra measuring from 10 to 15™™. From No. 19 back-
wards to the end of the series the vertebrse decrease slightly
in length and width. In specimen T in the same collection
there are 46 consecutive caudal vertebrae. These are of the
usual ichthyosaurian type, and represent an animal that had
an extremely long and slender tail. The reduction in the size
of the vertebrae occurs very near the body and within a dis-
tance of a few inches the vertebrae decrease in diameter over
one-half. The vertebrae in the area of reduction have reduced
margins, in fact in two of them the articulations nearly meet
upon the side of the centrum. This signifies that the tail was
extremely flexible near the body, which would make it of
great value in swimming, and without question this animal
could lash its sides with its tail. I have not noted anything of
this kind in the genus Ichthyosaurus. Although caudal verte-
brae from at least a half dozen diflEerent animals have been
examined, no trace of chevrons has been observed, and the
vertebrae lack chevron facets.

Pectoral Oirdle. — The coracoids are broadly elliptical bones,
anteriorly deeply and broadly notched ; posteriorly circular.
They thicken rapidly from the center to the interior margin



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80



W. C. Knight — Notes on the Oenue Baptanodon.



of the anterior half into a large elliptical facet with a rugose
surface. A facet measured 81 by 123"°. These facets unite
on the median symphysis, which must have made the girdle
very ridged during life. There was no evidence of an inter-




FiGUBE B. A. — Pectoral girdle incomplete, about \ natural size ; b. — Outline
of the interior margin of coracoid, about \ natural size.

clavicle, and the peculiar union of the coracoids precludes an
interdavicle of the regular Ichthyosaurian type. In conse-
quence the interdavicle in Baptanodon must be considered
rudimentary or wanting. The scapulae are rather heavy bones,
with broad notched proximal ends, that fit the projection of
the coracoids between the anterior notch and the glenoid cav-
ity. Clavicles are unknown to me.



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W. C, Knight — Notes on the Oenu% Baptanodon. 81

The most of the above information has been taken from
the S skeleton of the Wyoming collection, and I have found
it impossible to include this in the species already described
and for that reason propose the name of Baptanodon Marshi^
in honor of Prof. O. C. Marsh, who originated the generic name
Baptanodon. The accompanying figure of a front limb can be
considered as typical for tnis species.

Some Meaaurementa for Baptanodon* Marahi.

Humerus. M.

Length '190

Prox. width '127

Prox. thickness , '080

Distal width -130 +

Distal thickness , '050

Facet for ulna, length '080

Facet for radius, length '060

Facet for pisiform, length -010?

Ulna,

Width -069

Length '054

Radius,

Width -065

Length -046

Pisiform,

Width -030

Length -064

Coracoid,

Length

Width...

Median facet,

Length -123

Width -081

In comparing Baptanodon with Opthalmosaurus it will be
well to consider that in Baptanodon tne interclavicle is either
rudimentary or wanting, the absence of the intercentra between
the second and third vertebrse, the development of the large
facets upon the interior margins of the coracoids, the striking
differences in the development of the limbs, causing Baptano-
don to have been a much more powerful swimmer than its
European ally.

Geological Laboratory, University of Wyoming.

A.if. JouB. Soi.— FouBTH Sbbibb, Vol. XVI, No. 91.— July, 1903.
6



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82 O. F* Eaton — Characters of Pteranodon.



Abt. VIII. — The Characters of Pteranodon; by G. F.
Eaton. (With Plates VI and VII.)

A CAREFUL preparation of Pterodactyl material from the
Niobrara Cretaceous of western Kansas has been commenced
at the Yale University Museum, for the purpose of adding an
example of one of the gigantic species of the genus Pterano-
don Marsh, to the series of restorations of fossil vertebrates
recently attempted with success. Preparatory to this work, a
critical examination both of the fossils themselves and of the
literature based upon them has been made, and an excellent
opportunity has been thus aflforded to extend our knowledge
01 the skeleton of Pteranodon^ in regard to several important
points of structure. This, in turn, may be of great value in
determining the true position of the genus among the
Pterodactyls.

The large collection of these reptiles made by Prof. Marsh
and his assistants in the field, during a period including the
years 1870 to 1894:, and representing, according to Prof.
Marsh, the fossil remains of more than six hundred individ-
uals, was never completely examined and described by him.
His series of papers upon this unique order, which appeared
in this Journal, 1871 to 1882, were, at the time of publication,
considered by him as little more than preliminary notices.
No detailed work on the American Pterodactyls ever issued
from his hands, as his attention was constantly diverted by the
acquisition of other and not less valuable vertebrate fossils.

His researches both in field and in laboratory having
awakened the interest of the scientific world in the Kansas
Pterodactyls, it is not surprising to find other collectors and
authors engaged in similar investigations. While part of
Prof. Marsh's earlier work on this group was performed in a
somewhat hurried manner, the accuracy with which he seized
upon important osteological characters is amazing. In one
instance, at least, his opinion, after having been disputed
almost to the point of ridicule, proves to be much more
correct than that advanced by his critic. Considering his
great talent and the abundance of material at his command, it
18 to be regretted that Prof. Marsh did not pursue the study
further before laying it aside. Had he done so, he would
have prevented the misconceptions which have lately gained
credence.

The iSagittal Crest,

The most important correction to the prevailing idea of
Pteranodon is to be made in regard to the sagittal crest.
Prof. Marsh in describing the skull makes use of the follow-



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G. F. Eaton — Characters of Pteranodon, 83

ing words (this Journal, vol. xxvii. May, 1884): "an enor-
mous sagittal crest extends- far backward, and somewhat
upward.'' The accuracy of this statement is denied by Prof.
S. W. Williston (Kansas Univ. Quarterly, vol. i, No. 1, July,
1892), whose views have been accepted largely because of the
fact that he collected the head of Marsh's type of Pte>*anodon.
Material in the Tale Museum now shows that, contrary to
Williston's opinion, the elongation of the crest, as figured by
Marsh, was too conservative. Reference to Plate VI, figure 1,
will show its true form, taken from an actual specimen, which
is indicated by the continuous line. Marsh's incomplete
restoration is shown by the dotted line, while Williston's
figure of the skull, shorn of its crest, is reproduced carefully
in figure 2. Prof. Marsh laid emphasis on this character, and
it is of great importance that this error be corrected at once.
Following Williston's lead, Dr. S. P. Langley and Mr. F. A.
Lucas, both of the Smithsonian Institution, have perpetuated
the error in tlieir respective papers in the Annual Report of
that Institution for 1901.

In justice to Williston, it is perhaps only fair to quote him
verbatim (loc. cit): "As stated by me in the American
Naturalist, the type specimen of Pteranodmi^ also collected by
myself, was incomplete, and the figures of it, as given by
Marsh, are faulty." This statement can not be gainsaid. The
type suffered through the rough methods of collecting
employed in those days ; but the following clause has been
shown above to be incorrect : " The sagittal crest is large, but
not nearly so large as it is figured by Marsh, the outline of
whose figure is undoubtedly wrong."

To assign the cause of mistake on the part of another
writer may be considered a work of supererogation^'et I am
tempted to offer here a possible explanation of Williston's
misinterpretation of the sagittal crest of this reptile. At the

E resent time of writing, an incomplete Pterodactyl skull is
eing worked out at the Yale Museum, which will in all
probabilitv prove to be that of Nyctodactylus Marsh. The
crest, which is apparently entire, is of small size compared
with that of Pteranodon^ the measurement from occipital
condyle to tip of crest being only 49"°*, while the length from
occipital condyle to tip of beak was approximately 47®". In
general, the skull compares favorably with that shown in
Williston's restoration of Nyctodactylus given in the Ameri-
can Journal of Anatomy, vol. i. No. 3, May 26, 1902, where
he states that the outline is taken in part from a specimen of
Pteranodon Marsh, or Ornithostoma Seeley, as the genus was
then called. It is therefore fair to infer that the apparent
similarity of the two genera led Williston to draw uninten-



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84 O. K Eaton — Charactera of Pteranodon.

tionally upon the characters of Nyctodactyhis when making
his restoration of Ptercmodon. •

The Sitspensorium.

Another remarkable character of the skull of Pteranodon,
which belongs apparently to Nyctoddctylua also, is the articu-
lation of the mandibles with the quadrates. The distal end of
each quadrate has the form of a spiral groove, left-handed in
the right quadrate and right-handea in the left. The articular
elements of the mandibles have a reciprocal form. So perfect
is the mutual adjustment of these parts that, unless actual dis-
location took place, the act of opening the mouth must have
resulted either in a considerable widening of the lower
jaws posteriorly or in the forcing together of the quadrates.
Apparently the pterygoids and palatines serve as a rigid and
iminovable support to the quadrates, a condition which would
render movement of the latter impossible. In such case an
expansion of the lower jaws is, in my judgment, the only way
by which the lateral motion caused by the spiral articula-
tion could be taken up mechanically ; and this in the face of
the seemingly inflexible mandibular symphysis and the thor-
ough union of the mandibular elements.

The existing vertebrate oflFering the closest parallel in this
respect to Pteranodon is the Pelican. A careful inspection of
the suspensorium of this peculiar bird reveals a similar spiral
articulation between quadrates and mandibles, and it is recorded
that in the Pelican tne act of opening the mouth results also
in the widening of the jaws posteriorly. There has been some
speculation in regard to the habits of the American Ptero-
dactyls, but no definite conclusions have yet been reached.
Possibly the mechanical similarity between the mandibular
suspensorium of the Pelican and that of Pteranodon is to be
received as evidence of the possession of a gular pouch by this
Pterdactyl as well as by the bird.

Mr. Lucas has apparently arrived at the same conclusion
along another line of evidence. He says (loc. cit.) : " In the
peculiar shape of the lower, back portion of the beak there is
a suggestion of the former presence of a small pouch, like
that found in cormorants, and this would be in accord with
the supposed fish-eating habits of Ornithostorna'^^ {Pteranodon
Marsh).

The Pelvis.

A nearly perfect pelvis, recently worked out at the Yale
Museum, throws much light on the discussion of the charac-
ters of this important part of the skeleton of Pteranodon,
which has not been thoroughly understood and described by



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6r. F. Eaton — Cha/racterB of Pteranodon. 85

paleontologists. Three diagrams of this specimen are here
given, showing the side, top, and bottom views (Plate VII, fig-
ures 1, 2, and 3, respectively). It is not my intention at this



Online LibraryJohn RodgersThe American journal of science → online text (page 9 of 52)