Steve Cunningham, Baltimore, Maryland, USA
Striatolamia macrota Agassiz, 1843
Two possible subsets

From Mike Folmer's collection, Fisher/Sullivan site, early Eocene (Ypresian stage) Potapaco Member of the Nanjemoy Formation. A Random sample of 9,250 S. macrota teeth were sorted to position and then separated into two subsets labeled "a" and "b" as shown below.

Photos by S. Cunningham. Teeth have been coated with sublimated ammonium chloride to enhance detail.
The teeth of each position are depicted by three views of the same tooth. In the photographs below, all teeth are representative of the positional files of teeth from which they came.

All positional characters are derived from, and comparable to, extracted C. taurus teeth.

Distinguishing characters that define each subset are consistent from anterior to posterior teeth and throughout ontogeny. The 8 files for each lateral subset shown below are arbitrary. It is not know how many files S. Macrota had. However, the teeth depicted below represent the array of positional changes in the study set.

In the study set of 9,250 teeth, subset "a" totaled 5,665 teeth; while subset "b" totaled 3,298. The total count of first upper anterior teeth is 287 suggesting that only one subset has this position. The UA1 is consistent in characters and cannot be differentiated into subsets.

 

Graph Click here to see the positional tooth count and graph of positions for each subset
General differences
 Subset a
 Subset b
Courser striations Not as coursely striated or smooth
"U" shaped root interspace in lateral teeth "V" shaped root interspace on lateral teeth
Moderate protuberance Stronger protuberance
Profile view of labial side of laterals is nearly flat or convex Profile view of labial side of laterals is flat or obtuse angle of root and blade in lateral teeth
Crown rarely waisted (anterior teeth) Crown more often waisted (anterior teeth)
Bulky crown and root appearance Slender crown and root appearance
Lateral teeth bear distinct lateral cusplets Lateral teeth bear shoulder-like lateral cusplets
Mesial lateral cusplet reduces in size to the posterior Mesial lateral cusplet does not reduce in size
Root generally exhibits fine pits Root is generally smooth

Click on a tooth, group or row of teeth to see the larger image.
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Typical striations

a

 

Strong striations

b

 

Weak striations or smooth


Clear here to compare both typical striations

 

Typical upper lateral characters
a
 b
Striations well defined
Root generally pitted
Lateral cusplets well defined
"U" shaped lobe interspace
Striations are weak or not present
Root generally smooth or less pitted
Lateral cusplets less defined
"V" shaped lobe interspace

Click Here to compare both upper lateral examples

 

 

Typical lower lateral characters
a
 b
Striations are generally course
Root generally pitted
Lateral cusplets well defined
"U" shaped lobe interspace
Striations are weak or not present
Root generally smooth or less pitted
Lateral cusplets shoulder-like
"V" shaped lobe interspace

Click here to compare both lower lateral examples

 


UA1

The UA1 is consistent in appearance and cannot be reliably assigned to either subset. Their numbers total 287 out of 9,250 suggesting the position belonged to only one subset. The Characters and graph ally it with subset "b."


a
 UA2


b

Click here to compare UA2 - a and b


a
 UA3


b

Click here to compare UA3 - a and b

 

Teeth of the lower LA1 position (often called Symphysial teeth) are not considered in this study.

 


a
LA2


b

Click here to compare LA2 a and b

 


a
LA3


b

Click here to compare LA3 a and b

 


a
LA4


b

Click here to compare LA4 a and b

 

Teeth of the upper intermediate position are not considered in this study

 

 Upper lateroposterior
lingual view


a

 


b

Click here to compare upper lateral examples a and b - lingual view

________________________________________________________

Upper lateroposterior
profile view


a


  b

Click here to compare upper lateral examples a and b - profile view

_______________________________________________________

Upper lateroposterior
Labial view

a

 


b

Click here to compare upper lateral examples a and b - labial view

 

Lower lateroposterior
lingual view

a

b

Click here to compare lower lateral examples a and b - lingual view


Lower lateroposterior
profile view

a

b

Click here for lower lateral examples a and b - profile view

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lateroposterior
Labial view


a


b

Click here to compare examples a and b - labial view