Feeding habits of Antarctic Eocene penguins from a morphofunctional perspective

Haidr, Nadia Soledad; Hospitaleche, Carolina Acosta

doi:10.1127/0077-7749/2012/0217

Cited by 15 publications

(27 citation statements)

References 10 publications

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“…Whereas robust limb elements are common, cranial fragments are only rarely reported and are often in poor condition (e.g., Myrcha et al, 1990;Jadwiszczak, 2006b;. Aside from the specimens described here, only a few cranial remains have been mentioned in the literature, including two partially crushed braincases (Jadwiszczak, 2006b;, several partial beaks (Olson, 1985;Jadwiszczak, 2006b;, and the posterior portion of a braincase (Acosta Hospitaleche and Haidr, 2011;Haidr and Acosta Hospitaleche, 2012).…”

Section: Introductionmentioning

confidence: 79%

Endocranial anatomy of Antarctic Eocene stem penguins: implications for sensory system evolution in Sphenisciformes (Aves)

Tambussi¹,

Degrange²,

Ksepka

2015

Journal of Vertebrate Paleontology

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Penguins have a more than 60 million year long evolutionary history. Thus, stem lineage fossil taxa are key to understanding their evolution. Here, we present data on three virtual endocasts from stem penguin skulls collected from the Eocene La Meseta Formation of Seymour Island (Antarctica), along with comparative data from extant penguins and outgroups. These fossils appear to belong to three distinct species, and represent both the oldest (34.2 Ma) and the most basal penguin taxa that have yielded endocast data. Data collected from the fossils provide new support for several important shifts in neuroanatomy and cranial skeletal anatomy along the transition from stem to crown penguins, including (1) caudal expansion of the eminentia sagittalis, (2) an increase in the overlap of the telencephalon onto the cerebellum, (3) reduction of the bulbus olfactorius, and (4) loss of the interaural pathway. The large semicircular canal diameters of the Antarctic fossils as well as the more crownward stem penguin Paraptenodytes antarcticus together suggest that canal size increased in basal penguins relative to outgroup taxa but later decreased near the crown radiation. As in most other wing-propelled diving birds, the endocasts lack evidence of cerebellar folds and possess a relatively large floccular recess. Several aspects of the endocast morphology, including the exposure of the tectum opticum in dorsal view and the rostral displacement of the eminentia sagittalis away from the border of the cerebellum, are seen neither in crown penguins nor in Procellariiformes (the extant sister clade to Sphenisciformes) and so appear to represent unique characters of these stem taxa.

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Section: Introductionmentioning

confidence: 79%

Endocranial anatomy of Antarctic Eocene stem penguins: implications for sensory system evolution in Sphenisciformes (Aves)

Tambussi¹,

Degrange²,

Ksepka

2015

Journal of Vertebrate Paleontology

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“…The shape of the mandible is consistent with a spearbilled morphology seen in other Antarctic remains (Acosta Hospitaleche & Jadwiszczak, 2011;Haidr & Acosta Hospitaleche, 2017;Acosta Hospitaleche et al, 2019b) and similar to those of penecontemporaneous species from Peru (Perudyptes devriesi, mid-Eocene;Clarke et al, 2007;Icadyptes salasi, mid-to late Eocene;Clarke et al, 2007;Ksepka et al, 2008) as well as Paleocene penguins from New Zealand (Muriwaimanu tuatahi; Sequiwaimanu rosieae: Slack et al, 2006;Ksepka & Clarke, 2010;Mayr et al, 2018). The morphology of the mandible is consistent with the spear-billed morphology typical of stem species (Clarke et al, 2007;Ksepka & Clarke, 2010;Haidr & Acosta Hospitaleche, 2012;Haidr & Acosta Hospitaleche, 2017;Acosta Hospitaleche et al, 2019b). Measurements of the symphysis and estimates of mandible length indicate that the individual represented by the new mandible would have been larger than the older New Zealand species Muriwaimanu tuatahi (Slack et al, 2006) and between size estimates reported for other Eocene Antarctic spear-bills recovered from Seymour Island (Acosta Hospitaleche & Jadwiszczak, 2011;Haidr & Acosta Hospitaleche, 2017;Acosta Hospitaleche et al, 2019b).…”

Section: Discussionmentioning

confidence: 64%

“…The penguin mandible described here adds to the record of spear-billed penguins reported from the Eocene of Antarctica. Although fossil penguin cranial material is rare from Seymour Island, two beak morphotypes are known: long and narrow, spear-like shapes (proposed to indicate a primarily piscivorous diet) and shorter, broad morphs (proposed to indicate feeding on small crustaceans; Ksepka & Clarke, 2010;Acosta Hospitaleche & Jadwiszczak, 2011;Haidr & Acosta Hospitaleche, 2012;Haidr & Acosta Hospitaleche, 2017;Acosta Hospitaleche et al, 2019b). The shape of the mandible is consistent with a spearbilled morphology seen in other Antarctic remains (Acosta Hospitaleche & Jadwiszczak, 2011;Haidr & Acosta Hospitaleche, 2017;Acosta Hospitaleche et al, 2019b) and similar to those of penecontemporaneous species from Peru (Perudyptes devriesi, mid-Eocene;Clarke et al, 2007;Icadyptes salasi, mid-to late Eocene;Clarke et al, 2007;Ksepka et al, 2008) as well as Paleocene penguins from New Zealand (Muriwaimanu tuatahi; Sequiwaimanu rosieae: Slack et al, 2006;Ksepka & Clarke, 2010;Mayr et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…However, only a dorsal view is figured and the specimen lacks formal description, making it difficult to determine if the two fossils are from the same taxon. These fossils pertain to Paleogene penguins with spear-or dagger-like bills characteristic of stem species (Slack et al, 2006;Clarke et al, 2007;Clarke et al, 2010;Ksepka & Clarke, 2010;Jadwiszczak, 2011;Haidr & Acosta Hospitaleche, 2012;Acosta Hospitaleche et al, 2019b). However due to the new fossil's differences to assigned mandibular material (Acosta Hospitaleche et al, 2019b) and its partial preservation, TMM 44187-1 is not considered referable to any known Eocene taxon at this time.…”

Section: Gen Et Sp Indet (Figs 4m-4p)mentioning

confidence: 99%

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New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica

Davis

Torres

Musser

et al. 2020

PeerJ

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The middle–late Eocene of Antarctica was characterized by dramatic change as the continent became isolated from the other southern landmasses and the Antarctic Circumpolar Current formed. These events were crucial to the formation of the permanent Antarctic ice cap, affecting both regional and global climate change. Our best insight into how life in the high latitudes responded to this climatic shift is provided by the fossil record from Seymour Island, near the eastern coast of the Antarctic Peninsula. While extensive collections have been made from the La Meseta and Submeseta formations of this island, few avian taxa other than penguins have been described and mammalian postcranial remains have been scarce. Here, we report new fossils from Seymour Island collected by the Antarctic Peninsula Paleontology Project. These include a mammalian metapodial referred to Xenarthra and avian material including a partial tarsometatarsus referred to Gruiformes (cranes, rails, and allies). Penguin fossils (Sphenisciformes) continue to be most abundant in new collections from these deposits. We report several penguin remains including a large spear-like mandible preserving the symphysis, a nearly complete tarsometatarsus with similarities to the large penguin clade Palaeeudyptes but possibly representing a new species, and two small partial tarsometatarsi belonging to the genus Delphinornis. These findings expand our view of Eocene vertebrate faunas on Antarctica. Specifically, the new remains referred to Gruiformes and Xenarthra provide support for previously proposed, but contentious, earliest occurrence records of these clades on the continent.

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“…For the first time, the caudal end of the mandible is preserved in a Paleocene penguin, with the dorsal surface of the caudal end of the left ramus mandibulae being well exposed. Unlike in the crown group ( Figure 2C) and Eocene stem group Sphenisciformes [19,20], the mandible of CM 2018.124.4 lacks a retroarticular process and the processus medialis is proportionally larger and more pointed and is medially, rather than caudomedially, directed (amongst extant penguin, the caudomedial orientation of the processus medialis is less pronounced in Eudyptula and Spheniscus than in Aptenodytes). With regard to the above features and overall morphology, the caudal end of the mandible of CM 2018.124.4 actually more closely resembles the caudal end of the mandible of extant Fregatidae (frigatebirds; Figure 2D) than that of geologically younger Sphenisciformes.…”

Section: Description and Comparisonsmentioning

confidence: 94%

First Complete Wing of a Stem Group Sphenisciform from the Paleocene of New Zealand Sheds Light on the Evolution of the Penguin Flipper

Mayr

Pietri

Love³

et al. 2020

Diversity

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We describe a partial skeleton of a stem group penguin from the Waipara Greensand in New Zealand, which is tentatively assigned to Muriwaimanu tuatahi. The fossil includes the first complete wing of a Paleocene penguin and informs on previously unknown features of the mandible and tibiotarsus of small-sized Sphenisciformes from the Waipara Greensand. The wing is distinguished by important features from that of all geologically younger Sphenisciformes and documents an early stage in the evolution of wing-propelled diving in penguins. In particular, the wing of the new fossil exhibits a well-developed alular phalanx and the distal phalanges are not flattened. Because the wing phalanges resemble those of volant birds, we consider it likely that the wing feathers remained differentiated into functional categories and were not short and scale-like as they are in extant penguins. Even though the flippers of geologically younger penguins may favor survival in extremely cold climates, they are likely to have been shaped by hydrodynamic demands. Possible selective drivers include a diminished importance of the hindlimbs in subaquatic propulsion, new foraging strategies (the caudal end of the mandible of the new fossil distinctly differs from that of extant penguins), or increased predation by marine mammals.

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Feeding habits of Antarctic Eocene penguins from a morphofunctional perspective

Cited by 15 publications

References 10 publications

Endocranial anatomy of Antarctic Eocene stem penguins: implications for sensory system evolution in Sphenisciformes (Aves)

Endocranial anatomy of Antarctic Eocene stem penguins: implications for sensory system evolution in Sphenisciformes (Aves)

New mammalian and avian records from the late Eocene La Meseta and Submeseta formations of Seymour Island, Antarctica

First Complete Wing of a Stem Group Sphenisciform from the Paleocene of New Zealand Sheds Light on the Evolution of the Penguin Flipper

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