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 views126810
    Project overview3778
    Matrix views2499Matrix landing page (1931 views); Kohno 2006 modified matrix (294 views); walrus mandible and lower dentition (274 views);
    Media views85871Media search (6126 views); M86601 (375 views); M86654 (345 views); M86662 (382 views); M86648 (408 views); M101358 (299 views); M148227 (9 views); M86643 (391 views); M86669 (394 views); M86655 (334 views); M86221 (367 views); M148428 (6 views); M86649 (344 views); M86656 (336 views); M93589 (451 views); M86598 (376 views); M148291 (7 views); M86657 (385 views); M86674 (342 views); M86647 (331 views); M86652 (377 views); M86653 (365 views); M86644 (379 views); M107639 (43 views); M86720 (409 views); M86719 (393 views); M101444 (266 views); M101426 (295 views); M101435 (228 views); M107650 (40 views); M93595 (194 views); M93594 (188 views); M93593 (202 views); M93592 (194 views); M93591 (201 views); M93590 (366 views); M93580 (305 views); M86730 (349 views); M101348 (277 views); M148322 (9 views); M101345 (321 views); M101391 (312 views); M101452 (285 views); M101416 (341 views); M101447 (259 views); M101428 (272 views); M101338 (293 views); M101342 (318 views); M148289 (9 views); M148299 (11 views); M148298 (10 views); M148309 (12 views); M148313 (9 views); M148317 (5 views); M148321 (16 views); M101441 (237 views); M101449 (225 views); M148212 (14 views); M101377 (317 views); M101343 (294 views); M101423 (299 views); M101421 (308 views); M101379 (292 views); M86732 (371 views); M101334 (292 views); M106621 (41 views); M101396 (279 views); M101335 (285 views); M101353 (266 views); M101403 (267 views); M101431 (297 views); M101356 (313 views); M106613 (60 views); M101434 (164 views); M101436 (212 views); M101440 (196 views); M101445 (207 views); M101446 (283 views); M101448 (210 views); M101450 (221 views); M101451 (194 views); M101453 (239 views); M101433 (330 views); M101420 (304 views); M107658 (40 views); M101336 (306 views); M101337 (309 views); M101339 (311 views); M101340 (336 views); M101341 (298 views); M101344 (301 views); M101346 (277 views); M101347 (308 views); M101349 (330 views); M101350 (264 views); M101351 (290 views); M101352 (285 views); M101354 (296 views); M101355 (302 views); M101357 (353 views); M101359 (329 views); M101360 (313 views); M101361 (330 views); M101362 (369 views); M101363 (298 views); M101364 (312 views); M101365 (358 views); M101366 (324 views); M101367 (307 views); M101368 (285 views); M101369 (291 views); M101370 (390 views); M101371 (313 views); M101372 (334 views); M101373 (337 views); M101374 (340 views); M101375 (312 views); M101376 (332 views); M101378 (274 views); M101380 (269 views); M101381 (277 views); M101382 (376 views); M101383 (299 views); M101384 (319 views); M101385 (314 views); M101386 (310 views); M101387 (310 views); M101388 (315 views); M101389 (323 views); M101390 (272 views); M101392 (302 views); M101393 (306 views); M101394 (332 views); M101395 (357 views); M101397 (307 views); M101398 (328 views); M101399 (225 views); M101400 (264 views); M101401 (258 views); M101402 (310 views); M101404 (383 views); M101405 (300 views); M101406 (323 views); M101407 (298 views); M101408 (326 views); M101409 (323 views); M101410 (288 views); M101411 (331 views); M101412 (279 views); M101413 (329 views); M101414 (321 views); M101415 (311 views); M101417 (333 views); M101418 (328 views); M101419 (272 views); M101422 (308 views); M101424 (326 views); M101425 (321 views); M101427 (281 views); M101429 (312 views); M101430 (310 views); M101432 (309 views); M101437 (208 views); M101438 (251 views); M101439 (172 views); M101442 (220 views); M101443 (186 views); M107688 (51 views); M107642 (39 views); M86708 (320 views); M86684 (366 views); M86709 (349 views); M148204 (16 views); M107680 (67 views); M107661 (56 views); M107643 (50 views); M107668 (58 views); M107690 (68 views); M86699 (401 views); M86711 (325 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 (371 views); M86678 (386 views); M107685 (51 views); M106620 (47 views); M106614 (50 views); M86722 (336 views); M86681 (349 views); M106618 (44 views); M148189 (14 views); M86666 (379 views); M107689 (75 views); M106626 (52 views); M93584 (378 views); M86696 (369 views); M107636 (44 views); M107646 (52 views); M106611 (56 views); M107684 (47 views); M148318 (6 views); M148325 (8 views); M148338 (15 views); M86659 (347 views); M107657 (39 views); M86663 (381 views); M107673 (46 views); M101459 (40 views); M107647 (40 views); M106627 (41 views); M101468 (60 views); M148304 (6 views); M148358 (8 views); M86698 (343 views); M107651 (40 views); M107681 (51 views); M86688 (386 views); M86650 (397 views); M86665 (328 views); M86670 (319 views); M86668 (347 views); M86677 (371 views); M106634 (37 views); M86661 (399 views); M86673 (333 views); M107692 (50 views); M101464 (56 views); M101465 (40 views); M86671 (367 views); M106615 (86 views); M107676 (118 views); M86721 (357 views); M101469 (70 views); M106631 (41 views); M106617 (42 views); M86703 (350 views); M86728 (332 views); M107667 (59 views); M86642 (347 views); M86651 (341 views); M86700 (380 views); M86701 (357 views); M86702 (354 views); M86704 (378 views); M86705 (356 views); M86706 (339 views); M86707 (317 views); M86724 (440 views); M86725 (334 views); M86726 (365 views); M93581 (363 views); M93582 (340 views); M93583 (381 views); M93585 (371 views); M93586 (352 views); M93587 (378 views); M93588 (376 views); M86731 (394 views); M86600 (383 views); M86646 (360 views); M86660 (396 views); M86664 (363 views); M86667 (321 views); M86679 (372 views); M86680 (350 views); M86682 (341 views); M86683 (386 views); M86685 (369 views); M86686 (317 views); M86687 (336 views); M86689 (352 views); M86694 (418 views); M86695 (399 views); M86727 (378 views); M86729 (379 views); M86733 (346 views); M107677 (60 views); M107687 (51 views); M148283 (11 views); M107669 (59 views); M106619 (47 views); M107679 (50 views); M86672 (389 views); M86675 (379 views); M86676 (346 views); M86710 (342 views); M86713 (351 views); M86714 (327 views); M86718 (368 views); M86723 (341 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 (89 views); M107691 (57 views); M106610 (37 views); M106612 (51 views); M106616 (46 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 (49 views); M148417 (4 views); M148369 (5 views); M148233 (13 views); M148403 (4 views); M86717 (353 views); M107652 (42 views); M107644 (39 views); M107664 (45 views); M86716 (404 views); M101463 (53 views); M107665 (43 views); M101458 (47 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 (50 views); M148197 (5 views); M101454 (49 views); M101455 (43 views); M101456 (44 views); M101462 (70 views); M101466 (52 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 (6 views); M148476 (11 views); M148370 (6 views); M86715 (363 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 (7 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 (6 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 (11 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 (7 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 (9 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 list20374
    Documents list1634
    Taxon list9385
    Bibliography3269




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project331
    Matrix downloads60Kohno 2006 modified matrix (36 downloads); walrus mandible and lower dentition (24 downloads);
    Project downloads214
    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);