Project 530: R. W. Boessenecker,M. Churchill. 2013. A Reevaluation of the Morphology, Paleoecology, and Phylogenetic Relationships of the Enigmatic Walrus Pelagiarctos. PLOS ONE. 8 (1):e54311.
Specimen: † Pelagiarctos sp. (SDNHM/uncatalogued)

Abstract

Background
A number of aberrant walruses (Odobenidae) have been described from the Neogene of the North Pacific, including specialized suction-feeding and generalist fish-eating taxa. At least one of these fossil walruses has been hypothesized to have been a specialized predator of other marine mammals, the middle Miocene walrus Pelagiarctos thomasi from the Sharktooth Hill Bonebed of California (16.1–14.5 Ma).
Methodology/Principal Findings
A new specimen of Pelagiarctos from the middle Miocene “Topanga” Formation of southern California (17.5–15 Ma) allows a reassessment of the morphology and feeding ecology of this extinct walrus. The mandibles of this new specimen are robust with large canines, bulbous premolars with prominent paraconid, metaconid, hypoconid cusps, crenulated lingual cingula with small talonid basins, M2 present, double-rooted P3–M1, single-rooted P1 and M2, and a P2 with a bilobate root. Because this specimen lacks a fused mandibular symphysis like Pelagiarctos thomasi, it is instead referred to Pelagiarctos sp. This specimen is more informative than the fragmentary holotype of Pelagiarctos thomasi, permitting Pelagiarctos to be included within a phylogenetic analysis for the first time. Analysis of a matrix composed of 90 cranial, dental, mandibular and postcranial characters indicates that Pelagiarctos is an early diverging walrus and sister to the late Miocene walrus Imagotaria downsi. We reevaluate the evidence for a macropredatory lifestyle for Pelagiarctos, and we find no evidence of specialization towards a macrophagous diet, suggesting that Pelagiarctos was a generalist feeder with the ability to feed on large prey.
Conclusions/Significance
This new specimen of Pelagiarctos adds to the knowledge of this problematic taxon. The phylogenetic analysis conclusively demonstrates that Pelagiarctos is an early diverging walrus. Pelagiarctos does not show morphological specializations associated with macrophagy, and was likely a generalist predator, feeding on fish, invertebrates, and the occasional warm-blooded prey item.


Read the article »

Project DOI: 10.7934/P530, http://dx.doi.org/10.7934/P530
This project containsMatrices
  • 624 Media
  • 2 Matrices
  • 1 Document
  • 27 Taxa
  • 36 Specimens
  • 90 Characters
Total size of project's media files: 1513 MB

Download Project SDD File
Total scored cells: 2432
Total media associated with cells: 688
Total labels associated with cell media: 738
Characters
Total characters: 129
Total characters with associated media: 0
Total characters with media with labels: 0
Total character states: 249
Total character states with associated media: 79
Total character states with media with labels:79
Total unordered/ordered characters:129/0
Currently Viewing:
MorphoBank Project 530

    This research
    supported by



    Members

    member name taxa specimens media chars character
    media
    labels
    cell scorings
    (scored, NPA, "-")
    cell
    medialabels
    rules
    Morgan Churchill
    Project Administrator
    Last logged in 01/16/13
    2424527957202026
    (2026, 0, 0)
    2552180
    Robert Boessenecker
    Full membership
    Last logged in 11/07/12
    312973488156406
    (406, 0, 0)
    4334290


    Taxonomic Overview for Matrix 'M1174' (20 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] † Enaliarctos emlongi
    Last Modified in 12/05/13
    03970037282
    [2] † Pteronarctos goedertae
    Last Modified in 12/05/13
    039110035342
    [3] † Desmatophoca oregonensis
    Last Modified in 12/05/13
    03950033312
    [4] † Allodesmus gracilis
    Last Modified in 12/05/13
    039120027262
    [5] Monachus monachus
    Last Modified in 12/05/13
    03940035332
    [6] Erignathus barbatus
    Last Modified in 12/05/13
    04160033312
    [7] Callorhinus ursinus
    Last Modified in 12/05/13
    13860032302
    [8] † Proneotherium repenningi
    Last Modified in 12/05/13
    03960049472
    [9] † Kamtschatarctos sinelnikovae
    Last Modified in 12/05/13
    93050034322
    [10] † Neotherium mirum
    Last Modified in 12/05/13
    0393100872
    [11] † Imagotaria downsi
    Last Modified in 12/05/13
    04440065622
    [12] † Pelagiarctos sp.
    Last Modified in 12/05/13
    53420040382
    [13] † Pontolis magnus
    Last Modified in 12/05/13
    1383700102
    [14] † Gomphotaria pugnax
    Last Modified in 12/05/13
    53440034332
    [15] † Dusignathus santacruzensis
    Last Modified in 12/05/13
    03940045462
    [16] † Dusignathus seftoni
    Last Modified in 12/05/13
    73350036352
    [17] † Protodobenus japonicus
    Last Modified in 12/05/13
    13830043402
    [18] † Ontocetus emmonsi
    Last Modified in 12/05/13
    13830046452
    [19] † Valenictus chulavistensis
    Last Modified in 12/05/13
    192060017162
    [20] Odobenus rosmarus
    Last Modified in 12/05/13
    23740038332


    Taxonomic Overview for Matrix 'M1891' (23 Taxa)

    taxon unscored
    cells
    scored
    cells
    no cell
    support
    NPA
    cells
    "-" cellscell images labels on
    cell images
    member
    access
    [1] † Enaliarctos emlongi
    Last Modified in 12/05/13
    8828000002
    [2] † Pteronarctos goedertae
    Last Modified in 12/05/13
    8828100002
    [3] Callorhinus ursinus
    Last Modified in 12/05/13
    1898900002
    [4] † Desmatophoca oregonensis
    Last Modified in 12/05/13
    6868300002
    [5] † Allodesmus gracilis
    Last Modified in 12/05/13
    0929000002
    [6] Erignathus barbatus
    Last Modified in 12/05/13
    0929000002
    [7] Monachus monachus
    Last Modified in 12/05/13
    0909000002
    [8] † Prototaria primigenia
    Last Modified in 12/05/13
    47434300002
    [9] † Proneotherium repenningi
    Last Modified in 12/05/13
    8828100002
    [10] † Neotherium mirum
    Last Modified in 12/05/13
    1898700002
    [11] † Kamtschatarctos sinelnikovae
    Last Modified in 12/05/13
    49414000002
    [12] † Pseudotaria muramotoi
    Last Modified in 12/05/13
    54363600002
    [13] † Imagotaria downsi
    Last Modified in 12/05/13
    1968800002
    [14] † Pelagiarctos sp.
    Last Modified in 12/05/13
    56343300002
    [15] † Pontolis magnus
    Last Modified in 12/05/13
    3878600002
    [16] † Dusignathus santacruzensis
    Last Modified in 12/05/13
    35555300002
    [17] † Dusignathus seftoni
    Last Modified in 12/05/13
    16767000002
    [18] † Gomphotaria pugnax
    Last Modified in 12/05/13
    13777400002
    [19] Aivukus cedrosensis
    Last Modified in 12/05/13
    32585800002
    [20] † Protodobenus japonicus
    Last Modified in 12/05/13
    26646100002
    [21] † Ontocetus emmonsi
    Last Modified in 12/05/13
    2888700002
    [22] † Valenictus chulavistensis
    Last Modified in 12/05/13
    22686800002
    [23] Odobenus rosmarus
    Last Modified in 12/05/13
    2888800002


    Project views

    type number of views Individual items viewed (where applicable)
    Total project views121327
    Project overview3601
    Matrix views2385Matrix landing page (1840 views); Kohno 2006 modified matrix (283 views); walrus mandible and lower dentition (262 views);
    Media views82992Media search (5948 views); M86601 (358 views); M86654 (328 views); M86662 (364 views); M86648 (389 views); M101358 (291 views); M148227 (9 views); M86643 (374 views); M86669 (376 views); M86655 (316 views); M86221 (347 views); M148428 (6 views); M86649 (324 views); M86656 (318 views); M93589 (428 views); M86598 (357 views); M148291 (7 views); M86657 (366 views); M86674 (325 views); M86647 (315 views); M86652 (360 views); M86653 (345 views); M86644 (363 views); M107639 (43 views); M86720 (394 views); M86719 (381 views); M101444 (258 views); M101426 (287 views); M101435 (221 views); M107650 (40 views); M93595 (184 views); M93594 (177 views); M93593 (193 views); M93592 (185 views); M93591 (191 views); M93590 (350 views); M93580 (290 views); M86730 (335 views); M101348 (270 views); M148322 (9 views); M101345 (311 views); M101391 (303 views); M101452 (277 views); M101416 (333 views); M101447 (251 views); M101428 (264 views); M101338 (284 views); M101342 (307 views); M148289 (9 views); M148299 (11 views); M148298 (10 views); M148309 (11 views); M148313 (9 views); M148317 (5 views); M148321 (16 views); M101441 (230 views); M101449 (218 views); M148212 (14 views); M101377 (309 views); M101343 (286 views); M101423 (292 views); M101421 (300 views); M101379 (282 views); M86732 (358 views); M101334 (282 views); M106621 (41 views); M101396 (270 views); M101335 (272 views); M101353 (258 views); M101403 (258 views); M101431 (288 views); M101356 (304 views); M106613 (56 views); M101434 (156 views); M101436 (205 views); M101440 (191 views); M101445 (201 views); M101446 (274 views); M101448 (201 views); M101450 (213 views); M101451 (186 views); M101453 (231 views); M101433 (322 views); M101420 (296 views); M107658 (40 views); M101336 (294 views); M101337 (299 views); M101339 (303 views); M101340 (326 views); M101341 (292 views); M101344 (294 views); M101346 (268 views); M101347 (298 views); M101349 (322 views); M101350 (256 views); M101351 (283 views); M101352 (276 views); M101354 (288 views); M101355 (295 views); M101357 (346 views); M101359 (321 views); M101360 (304 views); M101361 (323 views); M101362 (360 views); M101363 (291 views); M101364 (301 views); M101365 (349 views); M101366 (313 views); M101367 (295 views); M101368 (276 views); M101369 (282 views); M101370 (381 views); M101371 (304 views); M101372 (324 views); M101373 (328 views); M101374 (328 views); M101375 (303 views); M101376 (323 views); M101378 (264 views); M101380 (259 views); M101381 (268 views); M101382 (368 views); M101383 (290 views); M101384 (310 views); M101385 (305 views); M101386 (301 views); M101387 (300 views); M101388 (308 views); M101389 (313 views); M101390 (264 views); M101392 (293 views); M101393 (297 views); M101394 (322 views); M101395 (349 views); M101397 (299 views); M101398 (319 views); M101399 (217 views); M101400 (255 views); M101401 (248 views); M101402 (301 views); M101404 (369 views); M101405 (291 views); M101406 (313 views); M101407 (289 views); M101408 (318 views); M101409 (313 views); M101410 (280 views); M101411 (322 views); M101412 (271 views); M101413 (322 views); M101414 (313 views); M101415 (303 views); M101417 (325 views); M101418 (321 views); M101419 (265 views); M101422 (300 views); M101424 (319 views); M101425 (313 views); M101427 (274 views); M101429 (302 views); M101430 (300 views); M101432 (301 views); M101437 (202 views); M101438 (244 views); M101439 (164 views); M101442 (213 views); M101443 (178 views); M107688 (51 views); M107642 (39 views); M86708 (305 views); M86684 (352 views); M86709 (335 views); M148204 (16 views); M107680 (67 views); M107661 (56 views); M107643 (50 views); M107668 (58 views); M107690 (68 views); M86699 (387 views); M86711 (311 views); M106633 (38 views); M107637 (45 views); M107672 (40 views); M106630 (54 views); M107683 (49 views); M106625 (36 views); M148293 (13 views); M107671 (52 views); M86645 (351 views); M86678 (370 views); M107685 (51 views); M106620 (47 views); M106614 (46 views); M86722 (320 views); M86681 (337 views); M106618 (44 views); M148189 (14 views); M86666 (361 views); M107689 (75 views); M106626 (52 views); M93584 (361 views); M86696 (356 views); M107636 (44 views); M107646 (52 views); M106611 (52 views); M107684 (47 views); M148318 (6 views); M148325 (8 views); M148338 (15 views); M86659 (332 views); M107657 (39 views); M86663 (361 views); M107673 (46 views); M101459 (40 views); M107647 (40 views); M106627 (41 views); M101468 (58 views); M148304 (6 views); M148358 (8 views); M86698 (328 views); M107651 (40 views); M107681 (51 views); M86688 (373 views); M86650 (380 views); M86665 (311 views); M86670 (301 views); M86668 (330 views); M86677 (354 views); M106634 (37 views); M86661 (383 views); M86673 (316 views); M107692 (50 views); M101464 (54 views); M101465 (40 views); M86671 (349 views); M106615 (82 views); M107676 (118 views); M86721 (343 views); M101469 (68 views); M106631 (41 views); M106617 (42 views); M86703 (336 views); M86728 (319 views); M107667 (59 views); M86642 (328 views); M86651 (323 views); M86700 (366 views); M86701 (344 views); M86702 (341 views); M86704 (364 views); M86705 (343 views); M86706 (325 views); M86707 (304 views); M86724 (426 views); M86725 (319 views); M86726 (348 views); M93581 (350 views); M93582 (325 views); M93583 (367 views); M93585 (357 views); M93586 (335 views); M93587 (363 views); M93588 (358 views); M86731 (379 views); M86600 (366 views); M86646 (342 views); M86660 (377 views); M86664 (344 views); M86667 (304 views); M86679 (357 views); M86680 (335 views); M86682 (327 views); M86683 (371 views); M86685 (353 views); M86686 (304 views); M86687 (323 views); M86689 (339 views); M86694 (403 views); M86695 (386 views); M86727 (363 views); M86729 (367 views); M86733 (333 views); M107677 (60 views); M107687 (51 views); M148283 (11 views); M107669 (59 views); M106619 (47 views); M107679 (50 views); M86672 (371 views); M86675 (362 views); M86676 (332 views); M86710 (327 views); M86713 (335 views); M86714 (314 views); M86718 (355 views); M86723 (327 views); M107648 (41 views); M148264 (7 views); M107634 (54 views); M107670 (98 views); M107662 (40 views); M148203 (15 views); M148240 (13 views); M148229 (13 views); M107702 (6 views); M148219 (5 views); M101460 (87 views); M107691 (57 views); M106610 (37 views); M106612 (47 views); M106616 (44 views); M106622 (40 views); M106623 (50 views); M106624 (40 views); M106628 (36 views); M106629 (51 views); M106632 (40 views); M106635 (35 views); M106636 (38 views); M106637 (52 views); M107653 (55 views); M101457 (47 views); M148417 (4 views); M148369 (5 views); M148233 (13 views); M148403 (4 views); M86717 (339 views); M107652 (42 views); M107644 (39 views); M107664 (45 views); M86716 (389 views); M101463 (51 views); M107665 (43 views); M101458 (45 views); M107633 (31 views); M107635 (51 views); M107638 (38 views); M107645 (43 views); M107649 (38 views); M107654 (56 views); M107655 (38 views); M107656 (46 views); M107659 (39 views); M107660 (39 views); M107663 (46 views); M107666 (53 views); M107674 (48 views); M107675 (40 views); M148327 (5 views); M107640 (42 views); M107641 (37 views); M107678 (37 views); M107682 (43 views); M107686 (60 views); M101470 (51 views); M101461 (48 views); M148197 (5 views); M101454 (49 views); M101455 (43 views); M101456 (42 views); M101462 (68 views); M101466 (50 views); M101467 (35 views); M148279 (6 views); M148266 (5 views); M148273 (5 views); M148281 (5 views); M148336 (4 views); M148251 (5 views); M148320 (5 views); M148285 (5 views); M148476 (11 views); M148370 (6 views); M86715 (349 views); M148411 (4 views); M107703 (11 views); M148355 (4 views); M148246 (11 views); M148250 (5 views); M148295 (6 views); M107698 (13 views); M148422 (3 views); M148282 (8 views); M148372 (5 views); M148371 (3 views); M148232 (14 views); M148466 (11 views); M148462 (8 views); M148396 (4 views); M148296 (6 views); M148190 (14 views); M148201 (14 views); M148288 (6 views); M148359 (4 views); M148418 (9 views); M148414 (4 views); M148300 (6 views); M148455 (11 views); M148277 (5 views); M148471 (7 views); M148188 (4 views); M148335 (6 views); M148334 (10 views); M148328 (6 views); M148310 (6 views); M148305 (5 views); M148218 (4 views); M148392 (4 views); M148444 (5 views); M148395 (5 views); M148375 (6 views); M148380 (6 views); M148376 (5 views); M148445 (4 views); M148389 (4 views); M148217 (3 views); M148337 (5 views); M148453 (3 views); M148187 (4 views); M148432 (9 views); M148440 (3 views); M148193 (15 views); M148276 (6 views); M148208 (12 views); M148443 (7 views); M148252 (6 views); M148228 (9 views); M107695 (9 views); M148362 (3 views); M148231 (11 views); M107697 (6 views); M148191 (12 views); M148449 (4 views); M148357 (4 views); M148260 (5 views); M148353 (3 views); M148424 (3 views); M148280 (4 views); M148456 (8 views); M148377 (5 views); M148195 (13 views); M148351 (4 views); M148226 (11 views); M148378 (5 views); M148454 (6 views); M148211 (3 views); M148404 (5 views); M148384 (3 views); M148235 (3 views); M148312 (4 views); M148457 (6 views); M148326 (6 views); M148248 (5 views); M148421 (4 views); M148434 (3 views); M148397 (3 views); M148215 (11 views); M148361 (2 views); M148294 (7 views); M148323 (5 views); M148430 (4 views); M148415 (4 views); M148290 (5 views); M148436 (4 views); M148216 (13 views); M148465 (7 views); M148393 (20 views); M148477 (10 views); M148441 (7 views); M148249 (5 views); M148413 (4 views); M148194 (11 views); M148381 (3 views); M148347 (3 views); M148416 (12 views); M148368 (4 views); M148461 (5 views); M148350 (5 views); M107693 (17 views); M148245 (12 views); M148200 (6 views); M148448 (4 views); M148223 (12 views); M148374 (3 views); M107699 (13 views); M148255 (4 views); M148267 (5 views); M148382 (4 views); M148330 (5 views); M148206 (13 views); M148447 (3 views); M148341 (5 views); M148354 (3 views); M148460 (6 views); M148213 (4 views); M148442 (5 views); M148367 (4 views); M148315 (6 views); M148429 (4 views); M148261 (6 views); M148275 (5 views); M148329 (8 views); M148307 (7 views); M148437 (3 views); M148463 (7 views); M148242 (4 views); M148287 (6 views); M148352 (3 views); M148324 (5 views); M148364 (4 views); M148258 (4 views); M148234 (14 views); M148423 (3 views); M148450 (6 views); M148303 (6 views); M148365 (3 views); M148247 (5 views); M148446 (3 views); M148214 (12 views); M148237 (4 views); M148205 (15 views); M148272 (8 views); M148311 (5 views); M148475 (7 views); M148363 (3 views); M107694 (5 views); M148230 (7 views); M148210 (12 views); M148302 (7 views); M148427 (3 views); M148472 (7 views); M148346 (4 views); M148394 (2 views); M148349 (3 views); M148221 (5 views); M107700 (7 views); M148222 (16 views); M148405 (8 views); M148316 (10 views); M148306 (6 views); M148225 (5 views); M148297 (6 views); M148257 (5 views); M148253 (4 views); M148278 (5 views); M148269 (5 views); M148199 (12 views); M148391 (5 views); M148348 (4 views); M148343 (10 views); M148340 (4 views); M148209 (15 views); M148387 (2 views); M148198 (4 views); M148409 (2 views); M148241 (5 views); M148333 (5 views); M148243 (5 views); M148301 (6 views); M148344 (5 views); M148431 (3 views); M148262 (7 views); M148331 (6 views); M148274 (5 views); M148224 (15 views); M148356 (2 views); M148292 (6 views); M148286 (5 views); M148464 (6 views); M148236 (6 views); M148220 (5 views); M148388 (2 views); M148401 (2 views); M107701 (6 views); M148196 (4 views); M148468 (11 views); M148254 (6 views); M148319 (5 views); M148410 (3 views); M148470 (7 views); M148314 (5 views); M148459 (12 views); M148345 (5 views); M148271 (5 views); M148192 (12 views); M148259 (4 views); M148268 (7 views); M148383 (2 views); M148469 (6 views); M148385 (2 views); M148402 (4 views); M148458 (10 views); M148386 (3 views); M148239 (12 views); M148412 (4 views); M148435 (2 views); M148474 (6 views); M148373 (5 views); M148270 (6 views); M148263 (5 views); M148439 (3 views); M148398 (2 views); M148400 (3 views); M148238 (13 views); M148244 (10 views); M148360 (2 views); M148473 (9 views); M148366 (5 views); M148332 (6 views); M148265 (8 views); M148207 (7 views); M148408 (3 views); M148399 (2 views); M148426 (4 views); M148420 (3 views); M148433 (2 views); M148390 (2 views); M148467 (7 views); M107696 (15 views); M148202 (14 views); M148256 (6 views); M148339 (4 views); M148284 (4 views); M148342 (3 views); M148308 (7 views);
    Specimen list19449
    Documents list1590
    Taxon list8173
    Bibliography3137




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project319
    Matrix downloads60Kohno 2006 modified matrix (36 downloads); walrus mandible and lower dentition (24 downloads);
    Project downloads202
    Document downloads7 (7 downloads);
    Media downloads50M86722 (2 downloads); M93595 (1 download); M93594 (1 download); M93593 (1 download); M93592 (1 download); M93591 (2 downloads); M93590 (1 download); M93589 (1 download); M93580 (1 download); M86649 (1 download); M86671 (1 download); M86669 (1 download); M86674 (1 download); M86221 (1 download); M101349 (1 download); M101352 (1 download); M101358 (1 download); M101356 (1 download); M101374 (1 download); M101377 (1 download); M101385 (1 download); M101382 (1 download); M101390 (2 downloads); M101393 (1 download); M101411 (1 download); M106613 (1 download); M106618 (1 download); M106628 (1 download); M148289 (1 download); M148294 (1 download); M148309 (1 download); M148308 (1 download); M148321 (1 download); M148343 (1 download); M86642 (1 download); M86600 (1 download); M86643 (1 download); M86645 (1 download); M86598 (1 download); M86648 (1 download); M86651 (1 download); M86652 (1 download); M86653 (1 download); M86654 (1 download); M86655 (1 download); M86656 (1 download); M86657 (1 download);