Fossil Evidence for Evolution of the Shape and Color of Penguin Feathers

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Science  12 Nov 2010:
Vol. 330, Issue 6006, pp. 954-957
DOI: 10.1126/science.1193604

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  1. Fig. 1

    Reconstruction of Inkayacu paracasensis in oblique anterior view showing recovered elements in white and photographs of the holotype specimen (MUSM 1444): skull and mandible in (A and C) dorsal, (B) ventral, and (D) lateral views; scapula in (E) lateral view and humerus in (F) posterior, (G) ventral, (H) anterior, and (I) distal views; femur in (J) dorsal, (K) medial, (L) ventral, and (M) distal views; patella in (N) anterior view; tibiotarsus in (O) lateral view; and tarsometatarsus in (P) proximal, (Q) distal, (R) anterior, and (S) plantar views. AC, acromion; AMB, pathway of m. ambiens tendon; ATR, anterior trochlear process; CBC, m. coracobrachialis caudalis insertion; CF, fibular crest; CNE, cnemial crests; CNS, coracobrachialis nerve sulcus; CT, coracoid tuberosity; DEN, dentary; GR, groove on premaxilla; IL, m. iliofemoralis and iliotrochantericus insertions; LF, lacrimal facet; LPVF, lateral proximal vascular foramen; MHC, medial hypotarsal crest; MC, medial condyle; MTR, middle trochlear process; PIII-1, manual phalanx III-1; PAL, palatine; PATH, pathology; PF, pectoralis fossa; PO, postorbital process; PS, parasphenoid rostrum; PTR, posterior trochlear process; SC, m. supracoracoideus insertion; SF, salt gland fossa; SU, surangular; T, tab-like process; TF, temporal fossa; V, vomer. Asterisks demarcate autapomorphies referenced in the diagnosis (10).

  2. Fig. 2

    The wing feathering of Inkayacu paracasensis. (A) Photograph and line drawing of the left wing (scale bar, 1 cm) showing location of insets and samples (circles) taken for scanning electron microscopy (SEM). (B) Close-up of the counterpart showing the surface of imbricated short covert feathers from the leading edge of the wing and (C) SEM of melanosomes in (B). (D) Close-up of the counterpart to the surface of the carpometacarpus with preserved melanized bases of covert feathers and (E) SEM of melanosomes from feather bases in (D) (melanosomes were not observed in surrounding matrix). (F) Close-up of tertiaries and (G) SEM of melanosomes in (F). (H) Secondaries and (I) SEM of melanosomes from (H). Scale bar for SEM images, 1 μm, and for insets, 3 mm. mc, carpometacarpus; r, radius; rl, radiale; t, tibiotarsus; u, ulna; ul, ulnare.

  3. Fig. 3

    Comparison of melanosome proportions and body contour feather morphology in (A and B) Inkayacu paracasensis and (C and D) representative extant penguins. (A) SEM of melanosomes preserved in the tip of (B) body contour feathers of I. paracasensis; (C) SEM of large, ellipsoidal melanosomes (shown, Eudyptula minor) from (D) similarly shaped body contour feathers (shown, Aptenodytes forsteri) in the penguin crown clade.

  4. Fig. 4

    Phylogenetic placement of Inkayacu paracasensis in a strict consensus cladogram of 45 most-parsimonious trees (MPTs) [Crown clade collapsed; see (10) for details of analysis]. Placement in a clade of Eocene giant penguins (X) implies an origin for the modified wing feathering, undifferentiated remiges, and broad rachis of body contour feathers (insets) no later than the early Eocene (10). Enlarged melanosomes are phylogenetically supported at minimum as a novelty of the penguin crown clade (insets). Stratigraphic distributions from (5). Fossil distributions are Antarctica, blue; New Zealand, green; Africa, dark gray; and South America, red.