[PaleoMammalogy • 2017] Dilophodelphis fordycei • A New Fossil Dolphin Provides Insight Into the Evolution of Supraorbital Crests in Platanistoidea (Mammalia, Cetacea) ---ScRaBBlE

Dilophodelphis fordycei

Boersma, McCurry & Pyenson, 2017 

  DOI: 10.1098/rsos.170022 
Image: A. Boersma  @Boersma_Alex 

Abstract

Many odontocete groups have developed enlarged facial crests, although these crests differ in topography, composition and function. The most elaborate crests occur in the South Asian river dolphin (Platanista gangetica), in which they rise dorsally as delicate, pneumatized wings anterior of the facial bones. Their position wrapping around the melon suggests their involvement in sound propagation for echolocation. To better understand the origin of crests in this lineage, we examined facial crests among fossil and living Platanistoidea, including a new taxon, Dilophodelphis fordycei, nov. gen. and sp., described herein, from the Early Miocene Astoria Formation of Oregon, USA. We measured the physical extent and thickness of platanistoid crests, categorized their relative position and used computed tomography scans to examine their internal morphology and relative bone density. Integrating these traits in a phylogenetic context, we determined that the onset of crest elaboration or enlargement and the evolution of crest pneumatization among the platanistoids were separate events, with crest enlargement beginning in the Oligocene. However, we find no evidence for pneumatization until possibly the Early Miocene, although certainly by the Middle Miocene. Such an evolutionary context, including data from the fossil record, should inform modelling efforts that seek to understand the diversity of sound generation morphology in Odontoceti.

KEYWORDS: cetacean, Platanistoidea, river dolphins, Miocene, pneumatization, computed tomography

Systematic palaeontology

Cetacea Brisson, 1762 

Odontoceti Flower, 1867 sensu Fordyce and Muizon, 2001 

Platanistoidea sensu Boersma and Pyenson 2016 

Platanistidae Gray, 1846  sensu Boersma and Pyenson 2016 

Dilophodelphis, gen. nov. 

Type and only included species. Dilophodelphis fordycei, sp. nov.

Etymology. From the Greek words di (double), lophos (crest) and delphis (dolphin), referring to the enlarged supraorbital crests on the dorsal surface of the skull, resembling twin mountain crests. This construction also evokes the dinosaur Dilophosaurus wetherilli Welles 1954, a double-crested theropod recovered from Early Jurassic sequences of the Kayenta Formation in Arizona, USA.

Dilophodelphis fordycei, sp. nov. 

Figure 1. Skull of Dilophodelphis (USNM 214911) in dorsal view.
(a) Illustrated skull with low opacity mask, interpretive line art and labels for skull elements. Dotted lines indicate uncertainty of sutures, and dashed lines highlight fossae. Hatched pattern indicates areas where sediment is obscuring the fossil. (b) Photograph of skull in dorsal view, photography by James Di Loreto, Smithsonian Institution. fr., frontals; max., maxilla; n., nasal; pmx., premaxilla; pmx. sac fossa, premaxillary sac fossa. 

Figure 2. Skull of Dilophodelphis (USNM 214911) in ventral view.
(a) Illustrated skull with low opacity mask, interpretive line art and labels for skull elements. Dotted lines indicate uncertainty of sutures, and dashed lines highlight fossae. Hatched pattern indicates areas where sediment is obscuring the fossil. (b) Photograph of skull in ventral view, photography by James Di Loreto, Smithsonian Institution. fr., frontal; max., maxilla; p., pterygoid; v., vomer. 

The endangered South Asian river dolphin, Platanista gangetica (middle), swimming alongside two of its fossil relatives: the longirostral Pomatodelphis inaequalis (bottom) and the new species Dilophodelphis fordycei (top). None of the species lived together at the same time. Glow-throughs to the skulls highlight the diversity in supraorbital crest shape and size among the members of this family.

Image: Alex Boersma  @Boersma_Alex 

Figure 3. Skull of Dilophodelphis (USNM 214911) in right and left lateral views.
 (a) Illustrated skull in right lateral view and (b) left lateral view with low opacity mask, interpretive line art and labels for skull elements. Dotted lines indicate uncertainty of sutures, and dashed lines highlight fossae. Hatched pattern indicates areas where sediment is obscuring the fossil. (c) Photograph of skull in right lateral view and (d) left lateral view, photography by James Di Loreto, Smithsonian Institution. exocc., exoccipital; m., maxilla; par., parietal; p., pterygoid; sq., squamosal; temp. fossa, temporal fossa; zyg. process, zygomatic process. 

Etymology: The species epithet honours Prof. R. Ewan Fordyce, FRSNZ, native New Zealander and prominent vertebrate palaeontologist. The epithet recognizes his extensive and long-lasting contributions to the field of marine mammal palaeontology, including his commitment to mentoring future scientists, especially in shaping the career paths of the authors herein. The epithet also honours his long-standing interest in the fossil marine mammal record of Oregon, which has yielded pivotal specimens for over a century, including Simocetus rayi Fordyce 2002, which he described.

Alexandra T. Boersma, Matthew R. McCurry and Nicholas D. Pyenson. 2017. A New Fossil Dolphin Dilophodelphis fordycei Provides Insight Into the Evolution of Supraorbital Crests in Platanistoidea (Mammalia, Cetacea). Royal Society Open Science.  DOI: 10.1098/rsos.170022

 twitter.com/boersma_alex/status/869939253207105536   twitter.com/MatthewRMcCurry/status/870060662180859906

 twitter.com/PyensonLab/status/870023491998887936   twitter.com/PyensonLab/status/869942790670741504

New, ancient dolphin species had weird skull crests australiangeographic.com.au/news/2017/06/new,-ancient-dolphin-species-had-weird-skull-crests   @ausgeo - Australian Geographic 

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

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شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[PaleoMammalogy • 2017] Urkudelphis chawpipacha • A New Tropical Oligocene Dolphin from Montañita/Olón, Santa Elena, Ecuador ---ScRaBBlE

Urkudelphis chawpipacha

 Tanaka, Abella, Aguirre-Fernández, Gregori & Fordyce, 2017  

DOI: 10.1371/journal.pone.0188380 

Abstract

A new small probable Oligocene dolphin from Ecuador represents a new genus and species, Urkudelphis chawpipacha. The new taxon is known from a single juvenile skull and earbones; it differs from other archaic dolphins in features including widely exposed frontals at the vertex, a dorsally wide open vomer at the mesorostral groove, and a strongly projected and pointed lateral tuberosity of the periotic. Phylogenetic analysis places it toward the base of the largely-extinct clade Platanistoidea. The fossil is one of a few records of tropical fossil dolphins.

Systematic paleontology

CETACEA Brisson, 1762

NEOCETI Fordyce & de Muizon, 2001

ODONTOCETI Flower, 1867

PLATANISTOIDEA Gray, 1863 sensu Fordyce, 1994

Comment: Urkudelphis chawpipacha shows these synapomorphies of the Platanistoidea (sensu Fordyce, 1994), as recognised previously by Tanaka and Fordyce [2017]: periotic with C-shaped parabullary sulcus; small articular rim, which forms a ridge anterolateral to posterior process of periotic and separated from it by a sulcus. Two phylogenies place Urkudelphis near the base of the Platanistoidea (sensu lato; including Platanistidae, Squalodelphis, Notocetus, Phocageneus, Otekaikea, Waipatiidae, Awamokoa and Squalodontidae [2017]).

Fig 2. Skull, Urkudelphis chawpipacha MO-1 (holotype) in dorsal view. Left, photo, right, line art.

Fig 4. Skull, Urkudelphis chawpipacha MO-1 (holotype) in right lateral view. Upper, photo, lower, line art.

Urkudelphis gen. nov.

Type species: Urkudelphis chawpipacha sp. nov.

Urkudelphis chawpipacha sp. nov.

Diagnosis: Urkudelphis chawpipacha is a small archaic odontocete with the following autapomorphic combination of characters: shallow antorbital notch (character 10); anteromedially oriented anterior edge of the supraorbital process (character 37); weakly dorsally convex nuchal crest in dorsoposterior view (character 119); approximately same sized apertures of the vestibular aqueduct and cochlear aqueduct (character 186); dorsoventrally thin pars cochlearis on the periotic (character 192); inner posterior prominence of the tympanic bulla is anterior to the outer posterior prominence (character 218); very strongly projecting and pointed lateral tuberosity; and an anteroposteriorly long accessory ossicle of the periotic. Urkudelphis chawpipacha differs from early branching odontocetes, including Agorophius, Ashleycetus, Simocetus, Mirocetus and Xenorophus in having the frontals on the vertex at a level behind the postorbital process; anteroposteriorly shorter and transversely wider frontals (approaching a square-shape rather than narrow and elongate); and parallel-sided posterior part of the ascending process of each maxilla forming a narrow elongate face. Urkudelphis differs from Early Miocene Papahu taitapu, Chilcacetus cavirhinus, Arktocara yakataga, Allodelphis pratti and Ninjadelphis ujiharai, having the frontals on the vertex flat and longer than the taxa above, which have more nodular and shorter frontals. Urkudelphis differs from Chilcacetus and Papahu in having a narrow premaxillary sac fossa. Urkudelphis chawpipacha also notably shows: frontals at the vertex invaded posteriorly by the interparietal; and long anteromedial projection of the palatine on the palate. Other diagnostic features of U. chawpipacha are shared with more-crownward Waipatiidae: a shallow suprameatal pit of the squamosal (character 152); an abruptly ventrally deflected anterior process of the periotic (character 172); and a nearly flat dorsal surface of the periotic in lateral view (character 181). In addition, Urkudelphis chawpipacha shares several characters with more-crownward Platanistoidea: a periotic with C-shaped parabullary sulcus (character 175); and a small articular rim, which forms a ridge anterolateral to the posterior process of the periotic and separated from it by a sulcus (character 195).

Holotype: MO-1, an incomplete skull (premaxilla, maxilla, vomer, pterygoid, frontal, parietal, interparietal, alisphenoid, squamosal and supraoccipital), including the right periotic, right tympanic bulla and right malleus.

Etymology: The generic name, Urkudelphis originates from Kichwa “urku” meaning mountain, referring to the type locality of Montañita, and Greek “delphis” for dolphin, which has been used widely as a suffix for dolphin generic names. Chawpipacha results from the combination of chawpi, meaning "half" or “middle” and pacha, meaning "the world" representing the equator, and thus Ecuador in Kichwa.

Type locality: MO-1 was found by one of the authors (JA) and several UPSE students in August 2015 in a boulder that collapsed from a cliff at the coastal locality here named Montañita/Olón (latitude 1°48'50.64" S, longitude 80°45'24.18" W). The Montañita/Olón (MO) locality (Fig 1) lies midway between the towns of Montañita and Olón (Santa Elena Province, Ecuador) and can only be accessed during low tides.

Conclusion: 

A new small dolphin from probable Oligocene (Chattian?) strata in Santa Elena, Ecuador is described as a new species and genus, Urkudelphis chawpipacha. The new taxon is characterized by: an anteromedially oriented anterior edge of the supraorbital process; weakly convex nuchal crest in dorsoposterior view; approximately same sized apertures of vestibular aqueduct and cochlear aqueduct; dorsoventrally thin pars cochlearis on periotic; and inner posterior prominence placed anterior to the outer posterior prominence. Urkudelphis chawpipacha differs from other Oligocene dolphins in the combination of: frontals on the vertex at a level posterior to the postorbital process; shorter and wider frontals; and parallel-sided posterior part of the ascending process of the maxilla. Phylogenetic analysis places it near the base of the largely-extinct clade Platanistoidea. The fossil is one of few fossil Neoceti reported from the equator, and is a reminder that Oligocene cetaceans may have ranged widely in tropical waters.

Yoshihiro Tanaka, Juan Abella, Gabriel Aguirre-Fernández, Maria Gregori and R. Ewan Fordyce. 2017. A New Tropical Oligocene Dolphin from Montañita/Olón, Santa Elena, Ecuador. PLoS ONE. 12(12); e0188380.  DOI: 10.1371/journal.pone.0188380

New ancient dolphin species Urkudelphis chawpipacha discovered in Ecuador http://phy.so/432980137 via @physorg_com

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.

[PaleoMammalogy • 2018] Macrosqualodelphis ukupachai • A New Large Squalodelphinid (Cetacea, Odontoceti) from Peru Sheds Light on the Early Miocene Platanistoid Disparity and Ecology ---ScRaBBlE

Macrosqualodelphis ukupachai  

Bianucci, Bosio, Malinverno, de Muizon, Villa, Urbina & Lambert, 2018

   DOI: 10.1098/rsos.172302 

Abstract

The South Asian river dolphin (Platanista gangetica) is the only extant survivor of the large clade Platanistoidea, having a well-diversified fossil record from the Late Oligocene to the Middle Miocene. Based on a partial skeleton collected from the Chilcatay Formation (Chilcatay Fm; southern coast of Peru), we report here a new squalodelphinid genus and species, Macrosqualodelphis ukupachai. A volcanic ash layer, sampled near the fossil, yielded the 40Ar/39Ar age of 18.78 ± 0.08 Ma (Burdigalian, Early Miocene). The phylogenetic analysis places Macrosqualodelphis as the earliest branching squalodelphinid. Combined with several cranial and dental features, the large body size (estimated body length of 3.5 m) of this odontocete suggests that it consumed larger prey than the other members of its family. Together with Huaridelphis raimondii and Notocetus vanbenedeni, both also found in the Chilcatay Fm, this new squalodelphinid further demonstrates the peculiar local diversity of the family along the southeastern Pacific coast, possibly related to their partition into different dietary niches. At a wider geographical scale, the morphological and ecological diversity of squalodelphinids confirms the major role played by platanistoids during the Early Miocene radiation of crown odontocetes.

KEYWORDS: Odontoceti, Squalodelphinidae, Early Miocene, Peru, phylogeny, palaeoecology

Systematic palaeontology

Cetacea Brisson, 1762

Neoceti Fordyce and Muizon, 2001

Odontoceti Flower, 1867

Platanistoidea Gray, 1863

Squalodelphinidae Dal Piaz, 1917

Type genus. Squalodelphis Dal Piaz, 1917

Other genera included. Huaridelphis, Medocinia, Notocetus, Phocageneus.

Macrosqualodelphis, gen. nov.

Etymology. From ‘Macro’, large, and ‘Squalodelphis’ the type genus of the family. Gender masculine.

Macrosqualodelphis ukupachai, sp. nov.

Holotype and only referred specimen. MUSM 2545 consists of a skull lacking the anterior portion of the rostrum, the ear bones, both mandibles and the hyoid bones. The ventralmost portion of the rostrum and of the basicranium is worn along a plane slightly anterodorsally sloping with respect to the horizontal plane of the skull (erupted portion of maxillary teeth, basioccipital crests, ventral part of exoccipitals and postglenoid processes of squamosals missing). MUSM 2545 also preserves three detached anterior teeth; the atlas, two thoracic, two lumbar and eight caudal vertebrae; the left humerus, radius and incomplete ulna; one phalanx and one metacarpal; and two small fragments of ribs.

Type locality. About 3 km south of the fossiliferous Cerro Colorado locality, Western Ica Valley, Ica Region, southern Peru. 710 m above sea level. The holotype was discovered and collected by one of the authors (M.U.).

Etymology. From ‘Uku Pacha’ (Uku = within, inside; Pacha = Earth), the Inca lower world, located below the Earth's surface, in reference to the discovery of the specimen buried in sediment.

Figure 16. Skeletal remains and inferred body outline of the squalodelphinids from the early Burdigalian of the Chilcatay Fm (Pisco Basin, Peru) and skeletal and body outline of the extant P. gangetica. Body lengths based on the Pyenson & Sponberg [2011] equation for the fossils and on Jefferson et al. [2008] for the extant P. gangetica.


Cranium of the holotype (MUSM 2545) of Macrosqualodelphis ukupachai, from the early Burdigalian of the Chilcatay Fm (Pisco Basin, Peru).

Figure 3. (a) Dorsal view; (b) corresponding explanatory line drawing;   Linear hatching indicates major breaks and cross-hatching areas covered by the sediment.

Figure 4. (a) Ventral view; (b) corresponding explanatory line drawing;  Linear hatching indicates major breaks, cross-hatching areas covered by the sediment and dark shading worn surface.

Figure 5. (a) Right lateral view; (b) corresponding explanatory line drawing; (c) left lateral view. Cross-hatching indicates supporting frame.

Conclusion: 

Macrosqualodelphis ukupachai is a new species of the extinct platanistoid family Squalodelphinidae based on a well-preserved partial skeleton collected from the Early Miocene (ca 19–18 Ma) fossiliferous beds of the Chilcatay Fm outcropping in the Western Ica Valley (southern coast of Peru). The age of this skeleton is further constrained via 40Ar/39Ar dating of a local volcanic ash layer to 18.78 ± 0.08 Ma (early Burdigalian).

Our phylogenetic analysis supports the referral of M. ukupachai to the monophyletic family Squalodelphinidae, of which it constitutes the earliest diverging lineage.

The main distinctive character of M. ukupachai is its large size: its estimated TBL is approximately 3.5 m, significantly larger than all other known squalodelphinids, including N. vanbenedeni (2.5 m) and H. raimondii (2.0 m), both also found in the Chilcatay Fm. Combined with cranial and dental features (robust rostrum less tapered than in other squalodelphinids, large temporal fossa, prominent nuchal and temporal crests, and more robust teeth), the large body size of M. ukupachai suggests that this squalodelphinid was able to prey upon larger prey items. Consequently, M. ukupachai would have been positioned higher along the local trophic chain than the roughly contemporaneous N. vanbenedeni and H. raimondii. Therefore, it is suggested that the squalodelphinid diversity, both locally and worldwide, could be related to their partition into different dietary niches, as is observed in the extant delphinids.

This new record further illustrates the first, Early Miocene, broad radiation of crown odontocetes in marine environments, with a major contribution of homodont platanistoids. This Early Miocene morphological and ecological diversification of platanistoids (including squalodelphinids) was followed by the radiation of delphinidans (porpoises, true dolphins and relatives) during the Middle–Late Miocene. The only extant survivor of the platanistoid ‘golden age’ is the endangered South Asian river dolphin P. gangetica, confined in freshwater ecosystems of the Ganges, Indus and Brahmaputra river basins.

Giovanni Bianucci, Giulia Bosio, Elisa Malinverno, Christian de Muizon, Igor M. Villa, Mario Urbina and Olivier Lambert. 2018. A New Large Squalodelphinid (Cetacea, Odontoceti) from Peru Sheds Light on the Early Miocene Platanistoid Disparity and Ecology. Royal Society Open Science. 5(4)  DOI: 10.1098/rsos.172302

 twitter.com/CoastalPaleo/status/986650946942980096

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روابط التحميل والمشاهدة، الروابط المباشرة للتحميل

من هنا

او

من هنا

شاهد هذا الفيديو القصير لطريقة التحميل البسيطة

منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات

كيف تحصل على مدونة جاهزة بآلاف المواضيع والمشاركات من هنا

شاهد قناة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على اليوتيوب لمزيد من الشرح من هنا

رابط مدونة منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات في أي وقت حــــتى لو تم حذفها من هنا
شاهد صفحة منتدى مدونات بلوجر جاهزة بألاف المواضيع والمشاركات على الفيس بوك لمزيد من الشرح من هنا

تعرف على ترتيب مواضيع منتدى مدونات بلوجر جاهزة بآلاف المواضيع والمشاركات (حتى لا تختلط عليك الامور) من هنا

ملاحظة هامة: كل عمليات تنزيل، رفع، وتعديل المواضيع الجاهزة تتم بطريقة آلية، ونعتذر عن اي موضوع مخالف او مخل بالحياء مرفوع بالمدونات الجاهزة بآلاف المواضيع والمشاركات، ولكم ان تقوموا بحذف هذه المواضيع والمشاركات والطريقة بسيطة وسهلة. ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــسلامـ.