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Alca carolinensis
Taxonomy
Alca carolinensis was named by Smith and Clarke (2011). Its type specimen is NCSM 13734, a partial skeleton, and it is a 3D body fossil. Its type locality is Lee Creek Mine, Yorktown Formation, which is in a Zanclean estuary/bay sandstone in the Yorktown Formation of North Carolina.
Synonymy list
| Year | Name and author |
|---|---|
| 2011 | Alca carolinensis Smith and Clarke p. 23 figs. Fig. 13 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Alca carolinensis Smith and Clarke 2011
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| N. A. Smith and J. A. Clarke 2011 | Proposed autapomorphies of Alca carolinensis include the presence of a dorsally projecting tubercle on the posterior apophysis of the furcula (37:1) and bicipital tubercle of the proximal radius positioned distal to and separated from the proximal ligamental papilla (90:1; sensu Howard 1929). These features are not seen in any other extant Alcidae or in any extinct Pan-Alcidae for which these elements are known. However, among other Alca, furculae are known only from A. torda and A. olsoni, and radii are known only from A. torda, A. olsoni, and A. stewarti. Alca carolinensis can be differentiated from A. olsoni by the absence of a distinct ridge that borders the m. brachialis scar on the ventral surface of the proximal ulna (98:1). Like A. torda and A. grandis, the ulna of A. carolinensis has a rounded anterior margin of the dorsal cotylar prominence (97:0), rather than a straight margin as in A. olsoni and A. stewarti. The intercondylar sulcus is less deeply incised than in A. olsoni, A. stewarti, A. grandis, and A. torda (104:1). Alca carolinensis is further differentiated from A. grandis by the lack of a posterodorsally projecting tubercle on the distal surface of the ventral condyle (84:0; Fig. 10). Alca carolinensis is further differentiated by the concave ventral/sternal margin of the procoracoid process of the coracoid (50:0). This margin is convex in A. torda, A. stewarti, A. olsoni, and A. grandis. Associated specimens that would allow referral of coracoids to A. ausonia and A. minor are not known. The dorsal margin of the primary pneumotricipital fossa (i.e., crus dorsale fossae; Baumel and Witmer 1993) of A. carolinensis and other Alca except A. torda and A. minor ends proximal to the junction of the bicipital crest with the humeral shaft (65:0). The distal margin of the primary pneumotricipital fossa (i.e., crus ventrale fossae; Baumel and Witmer 1993) of A. carolinensis and other Alca except A. minor and specimens referred to A. ausonia is straight rather than concave (70:1). With the exception of A. olsoni, with which it shares similar proportions, A. carolinensis can be differentiated from other Alca on the basis of size (Table 4; difference between greatest length of humeri: ~61%> A. minor; ~30.6%> A. torda; ~15.1%> A. ausonia; 5.3%> A. grandis; 8.6%< A. stewarti). |
Measurements
No measurements are available
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| Source: subo = suborder, o = order | |||||
| References: Benton 1983, Marsh 1875, Bush and Bambach 2015 | |||||