ANAPTOMORPHIDAE

ANEMORHYSIS SUBLETTENSIS

(Gazin) (Plate3, figure i)

Following description of

Anemorhysis

sublettensis (1952, ^p. 24) as a possible

form

of Paratetonius, it

was

realized that the type of Paratetonius, P. steini,

was

not distinct

from

Tetonius homunculus.

As

a consequencethe

name Anemorhysis was

proposed (1958,^p. 25) for the

La Barge form and

to this

genus was

allocated the Lysite species "Tetonius"

muscidus Matthew

(pi. 3, ^fig. 2).

No new ma-

terial of

A.

sublettensis has

come

to light but specimens representing a

form

that

may

beclosely related

were found

inthe

lowermost

beds of the

Knight

near Bitter Creek.

These

are described below.

TET0N0IDES,7 new

genus Type.

—

Tetonoidespearcei,

new

species.

Generic characters.

— Resembling

Tetonius but

P4

relatively

much

^

From

its resemblance to Tetonius.

NO. I

LOWER EOCENE MAMMALIAN FAUNAS — ^GAZIN

35 smaller

and

lower crowned, with

much

better-developed paraconid

and

metaconid, better-defined talonid

and

well-defined externalcingu- lum.

Lower

molars Tetonius-like but labial wall with a relatively

much

shorter slope

and

a well-developed cingulum.

Apex

of trigonid in lower molars transversely

narrower and

less

compressed

antero- posteriorlythan in

Anemorhysis.

TETONOIDES

PEARCEI,s

new

species (Plate 3,figures 3-5; plate5, figure i)

Type.

—

^Right

^ramus

^ofmandible with P3-M2,

U.S.N.M. No.

22426.

Horizon and

^locality.

— ^Lowest

^{beds of}

^{Knight member, Gray}

Bull

(Sand

Coulee) equivalent, i\ miles south of Bitter

Creek

Sta- tion,

Sweetwater

County,

Wyo.

Specific characters.

—

Size of teethveryclose to those of "Tetonius"

tenuiculus Jepsen, but paraconid

and

metaconid of

M2 and M3

dis- tinctly closer together,

and

anterior crest

from

protoconid

on

these teeth with greater anteroexternal deflection.

Material.

—

^{In addition to the type (pi.} 5, ^fig. i),

which

includes the posterior premolars as well as the anterior molars, there are

two jaws

that exhibit all three molars

(U.S.N.M. No.

22382, see pi. 3, fig.4;

and U.S.N.M. No.

22799), ^

j^w

with only

M2

but exhibiting the anterior alveoh

(U.S.N.M. No.

22383, ^see pi. 3, ^fig. 3),

and

a

jaw

portionwith P3

and

P4

(Y.P.M. No.

14084, seepi. 3, ^fig. 5)

and

the

more forward

^alveoli. All of these except for

No. 22799 were found

atthe Bitter

Creek

locality.

No. 22799 was

collected

by Henry W.

Roehler

from

a level 1,126 feet

below

the Tipton tongue

on

the west side of the

Rock

Springs uplift, inassociationwith

Haplomylus.

Among

the

Gray

Bull materialswith

which

comparisons

were made

are threelower

jaws

that

beyond

doubt represent Jepsen's "Tetonius"

tenuiculus

which

I

am

here referring to Tetonoides.

One

of these,

A.M. No. 15066

with

P4-M2

(pi. 3, ^fig. 6), questionably referred

by Matthew

to "Tetonius" musculus, is, as Jepson's type,

from

low in the

Gray

Bull.

A

^{specimen in the National}

Museum, U.S.N.M.

No. 19154

(pi. 3, ^fig. 7), with

M2 and M3 from Elk

Creek, also

may

wellbe

from low

inthe

Gray

Bull butthis is uncertain.

A

^thirdlower

jaw was

recently observedinthe collections atPrinceton University.

The

molars in these

jaws

bear a strong resemblance to those in Tetonius homunculus, but with the differences noted above,

and

are of a size to occlude well with the type

upper

teeth of Tetonoides tenuiculus. Additional correspondence with the type of T. tenuiculus

s

Named

forFranklin L. Pearce

who

aided

me

on somany field expeditions.

is seen in the relatively smaller fourth premolar than in Tetonius homunculus.

Description.

— ^The

^{formula for the lower} dentition of Tetonoides pearcei is _{2, T, J, r-}

The

anterior incisor is enlarged but moderately erect, as in T. homunculus,

and

the second of the

two

incisors is small with its elongate root posterolateral to the other.

The

canine alveolus is of

moderate

size with a

more

nearly circular outline than the others.

An

alveolus for a P2 is only a little smaller than that of thecanineinthetype

and

in

Y.P.M. No.

14084, butanteroposteriorly

more

flattened in

U.S.N.M. No.

22383.

The

presence of

P2

in T.

pearcei isa rather primitive feature in

comparison

with Tetonius ho- munculus,asitis for

anaptomorphids

ingeneral,

and may

wellbesus- pected for T. tenuiculus also, although

none

of the

known

lower

jaws

of the latteris sufficientlycompletetodeterminethis feature.

Larger

T.

homunculus

with its relatively larger P4

shows no

evidence of a Pa.

P3

in T. pearceiis two-rooted

and

only a little smaller than P4.

It lacks themetaconid seen

on

P4,

and

the small paraconid is not de- flected

inward

as in P4. P4 has the relatively very small size charac- terizing T. tenuiculus, but the outer wall at the

cingulum

is a little

longer anteroposteriorly.

The

paraconid appears alittle higher

on P4 and

themetaconid lower

and

perhapslessdeveloped thaninT. tenuicu- lus, as represented

by A.M. No.

15066.

The

talonid of

P4

^is

much

alike inthe

two

species. It is of further interest to note thatthe ex- ternal

cingulum

of P4,

and

of the lower molars as well, is better de- veloped in both T. pearcei

and

T. tenuiculus thanin T.

homunculus.

Usually P4

and Mi

in T.

homunculus,

with their vertically

more

elongateouterwall,

show

littleor

no

evidence of theexternal shelf like

cingulum

conspicuous in the smaller form.

Although

the lower

jaws

of Tetonoides pearcei

and

T. tenuiculus are alike in certain details, including size, in

which

they differ

from

T. homunculus, the

molar

trigonids

(Mg and M3)

appear to be sig- nificantly different

between

the

two

smaller species.

While

the inner

and

outer walls of the

crowns

converge

upward,

almostas noticeably as in T.

homunculus,

so thatthe

apex

of the trigonid isrelativelynar-

row —

in comparison, for example, with

Anemorhysis

suhlettensis

—

the paraconid in T. pearcei is rather closer to the metaconid than it isinT. tenuiculus. Inthis respect the

crown

resembles

Anemorhysis.

Also it

was

noted that the crest

from

theprotoconid in the posterior lower molars

makes

a

more pronounced

anteroexternal deflection as

itextends

from

theprotoconidtothe anterior

margin

of the paraconid.

This condition, together with the shorter distance

between

the apices

NO. I

LOWER EOCENE MAMMALIAN FAUNAS — ^GAZIN

37 of the paraconid

and

metaconid, gives the trigonid a

somewhat

less triangularappearance thanin T. tenuicuhis.

Were

itnot for the

more

noticeable

upward

convergence of the in- ner

and

outer walls of the lower molars, T. pearcei

might

well have beenreferredto

Anemorhysis. A.

suhlettensis,aslightlysmaller form, otherwise

shows

a shorter

and

broader trigonid

and

a relatively longertalonid. Anteroposterior

development

of the talonidalsochar- acterizes P4 in

A.

suhlettensis.

M3

in

Anemorhysis muscula

is very close in size to this tooth in T. pearcei

(U.S.N.M.

Nos.

22382 and

22799),

and

although

M3

is not

known

in

A.

suhlettensis, the antero- posteriorly shorter trigonid

and

slightly

more

erect outer wall of the protoconid strongly suggest that

A. muscula

is

more

properly re- ferred to

Anemorhysis

than to Tetonoides. I strongly suspect that Tetonoides is close to the line of development for

Anemorhysis.

MEASUREMENTS IN MILLIMETERSOFLOWERTEETH OF Tetonoides pearcei

and

Tetonoides tenuicuhis

T. pearcei T. tenuiculus

Y.P.M.U.S.N.M. U.S.N.M. A.M. U.S.N.M.

No. No. No. No. No.

14084 22382 22383 15066 19154

P2-P4 (at alveoli) 2.8 2.7

Mi-Ms, inclusive

54

Ps, anteroposterior diameter:

transverse diameter 1.3:1.0 P4, anteroposterior diameter

:

transverse diameter 1.5:1.3 1.5:1.4

Ml, anteroposterior diameter

:

transverse diameter 1.8:1.5 1.8:1.6

M2, anteroposterior diameter

:

transverse diameter 1.7:1.6 1.8:1.6 1.8:1.7 1.7:1.6 Ma, anteroposterior diameter

:

transversediameter ^2.2:1.4 2.1:1.3

ABSAROKIUS,

nearA.

ABBOTTI

(Loomis) (Plate5,figure3)

A

lower

jaw from

the

Red

Desert area, that

McGrew

^assures

me

is

from

the

Gray

Bull level, is

found

to represent Ahsarokius rather than Tetonius.

The

specimen (U. of

Wyo. No.

1644, see ^pi. _5,

fig.3), ^collected

by Henry W.

Roehlerin

SW^NE:!

sec. 10, T.

24

^N., R. 100

W.,

includes

P3-M3 and

exhibits allthe alveoli anterior to P3.

The

molar teeth are relatively small but can be

matched

ⁱⁿ aparticu- larlysmallspecimen of

A.

ahhotti

(A.M. No.

14672)

from

the Lysite, but P4 in the

Red

Desert specimen is a little larger.

The

relatively

38 SMITHSONIAN MISCELLANEOUS COLLECTIONS

VOL, I44