[PaleoMammalogy • 2017] Mystacodon selenensis • Earliest Mysticete from the Late Eocene of Peru Sheds New Light on the Origin of Baleen Whales ---ScRaBBlE

Mystacodon selenensis 

Lambert, Martínez-Cáceres, Bianucci, Celma, Salas-Gismondi, Steurbaut, Urbina & Muizon, 2017

 DOI:  10.1016/j.cub.2017.04.026 

Highlights

• An ancient whale is described based on a skeleton from the late Eocene of Peru

• It is identified as the earliest known mysticete (baleen whales and relatives)

• Skeletal anatomy provides crucial information on archaeocete-mysticete transition

• This whale is interpreted as specialized for suction and possibly benthic feeding

Summary

Although combined molecular and morphological analyses point to a late middle Eocene (38–39 million years ago) origin for the clade Neoceti (Odontoceti, echolocating toothed whales plus Mysticeti, baleen whales, and relatives), the oldest known mysticete fossil dates from the latest Eocene (about 34 million years ago) of Antarctica. Considering that the latter is not the most stemward mysticete in recent phylogenies and that Oligocene toothed mysticetes display a broad morphological disparity most likely corresponding to contrasted ecological niches, the origin of mysticetes from a basilosaurid ancestor and its drivers are currently poorly understood. Based on an articulated cetacean skeleton from the early late Eocene (Priabonian, around 36.4 million years ago) of the Pisco Basin, Peru, we describe a new archaic tooth-bearing mysticete, Mystacodon selenensis gen. et sp. nov. Being the geologically oldest neocete (crown group cetacean) and the earliest mysticete to branch off described so far, the new taxon is interpreted as morphologically intermediate between basilosaurids and later toothed mysticetes, providing thus crucial information about the anatomy of the skull, forelimb, and innominate at these critical initial stages of mysticete evolution. Major changes in the morphology of the oral apparatus (including tooth wear) and flipper compared to basilosaurids suggest that suction and possibly benthic feeding represented key, early ecological traits accompanying the emergence of modern filter-feeding baleen whales’ ancestors.

Systematics

Cetacea

Pelagiceti

Neoceti

Mysticeti

Mystacodontidae fam. nov.

Mystacodon selenensis gen. et sp. nov.

Etymology: From ancient Greek mystacos (“moustache”) in reference to the suborder Mysticeti and odontos (“tooth”), “mysticete with teeth,” and from Selene, the Greek goddess of the moon, in reference to the Playa Media Luna type locality.

Figure 1: Cranium, Mandible, and Teeth of Mystacodon selenensis gen. et sp. nov. MUSM 1917.

Cranium in dorsal (A), left lateral (B), and ventral (C) views; detail of left posterior lower teeth in lateral view (D); left mandible in lateral (E) and dorsal (F) views; and three detached anterior lower teeth (from left to right: incisor, incisor/canine, and ?p1) in lingual or labial and occlusal views (G).

aof, antorbital foramina; apm, antorbital process of maxilla; bn, bony nares; C, upper canine; c, lower canine; cp, coronoid process; ep, embrasure pit; I1–I3, upper incisors; i1–i3, lower incisors; iop, infraorbital plate; ju, jugal; la, lacrimal; M1 and M2, upper molars; m1–m3, lower molars; maf, mandibular fossa; mf, mental foramina; mg, mesorostral groove; mx, maxilla; na, nasal; nc, nuchal crest; P1–P4, upper premolars; p1–p4, lower premolars; pa, parietal; pmx, premaxilla; prpf, preorbital process of frontal; pspf, postorbital process of frontal; sq, squamosal; sym, mandibular symphysis; zpm, zygomatic process of maxilla; zyg, zygomatic process of squamosal. Scale bars for (A)–(C), (E), and (F), 200 mm; for (D), 20 mm; and for (G), 10 mm.   

Two Mystacodon selenensis individuals diving down to catch eagle rays along the seafloor of a shallow cove off the coast of present-day Peru.

Illustration: Alberto Gennari 

Holotype: Museo de Historia Natural, Universidad Nacional Mayor de San Marcos (MUSM; Lima, Peru) 1917, partial skeleton including cranium, mandibles, teeth, cervical, thoracic, lumbar and caudal vertebrae, ribs, partial right and left forelimbs, and left innominate.

Locality: Playa Media Luna, southern part of Pisco Basin, southern coast of Peru, ...

Horizon: Middle part of the Yumaque Formation, 77 m above the base; lower part of calcareous nannofossil zone NP19/20 of Martini; dated at 36.4 million years ago based on age estimations used by Agnini et al. [2014]; early late Eocene (early Priabonian; see Figures S1A and S1D, Table S1, and STAR Methods for the biostratigraphic and biochronological interpretations).

Diagnosis: MUSM 1917 is identified as a Neoceti based on the following derived characters, absent in basilosaurid archaeocetes: partly open mesorostral groove; anteroposteriorly elongated rostral portion of maxilla; loss of sagittal crest; supraoccipital shield anterodorsally inclined; apex of zygomatic process of squamosal nearly contacting postorbital process of frontal; and distal epiphysis of the humerus divided in two angled radial and ulnar facets. It can be referred to the Mysticeti due to the following combination of derived characters: dorsoventrally thin lateral edge of maxilla on rostrum; presence of an antorbital process of the maxilla; presence of a maxillary infraorbital plate; and triangular supraoccipital shield. It is further diagnosed by two possibly autapomorphic features: nasal anteroposteriorly longer than frontal plus parietal and strong tuberosity on anterior edge of radius; two additional derived characters: posteriormost upper tooth anterior to level of antorbital process of maxilla and broad-based rostrum (ratio between width of skull at rostrum base and width at postorbital process > 0.8); and a series of plesiomophic features: supraoccipital shield not extending anterior to anterior level of squamosal fossa, only two dorsal infraorbital foramina, a basilosaurid dental formula 3.1.4.2/3.1.4.3, no wide diastemata between posterior cheek teeth, sutured mandibular symphysis, and well-defined acetabulum on innominate. Finally, MUSM 1917 lacks cranial synapomorphies of Odontoceti: facial concavity, presence of premaxillary foramen and premaxillary sac fossa, and posterior expansion of maxilla over the supraorbital region (Figures 1, 2, 3, and S2).

Members of the excavation team digging around the skeleton of Mystacodon selenensis at the Media Luna locality in the Pisco Basin, Peru.

photo: Giovanni Bianucci  

Olivier Lambert, Manuel Martínez-Cáceres, Giovanni Bianucci, Claudio Di Celma, Rodolfo Salas-Gismondi, Etienne Steurbaut, Mario Urbina and Christian de Muizon. 2017. Earliest Mysticete from the Late Eocene of Peru Sheds New Light on the Origin of Baleen Whales. Current Biology.  In Press.  DOI:  10.1016/j.cub.2017.04.026

    

36m-year-old fossil discovery is missing link in whale evolution, say researchers TheGuardian.com/science/2017/may/11/36m-year-old-fossil-discovery-is-missing-link-in-whale-evolution-say-researchers-mystacodon-selenensis

Baleen whales' ancestors were toothy suction feeders http://phy.so/413697728 via @physorg_com

This ancient whale likely sucked prey into its mouth like a giant vacuum cleaner https://www.theverge.com/tldr/2017/5/11/15610764/mysticete-whale-ancestor-suction-feeder-evolution  via @Verge

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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] Coronodon havensteini • The Origin of Filter Feeding in Whales ---ScRaBBlE

Coronodon havensteini  

Geisler, Boessenecker, Brown & Beatty, 2017

Illustration: A. Gennari DOI: 10.1016/j.cub.2017.06.003 

 Highlights

• A new species of 30 million year old whale has been found near Charleston, South Carolina

• This new species is a relative of modern baleen-bearing whales but retains teeth

• Its molars are large, multi-cusped, and overlapping and were used for filter feeding

• Filter feeding evolved before baleen; early whales had teeth and baleen

Summary

As the largest known vertebrates of all time, mysticetes depend on keratinous sieves called baleen to capture enough small prey to sustain their enormous size. The origins of baleen are controversial: one hypothesis suggests that teeth were lost during a suction-feeding stage of mysticete evolution and that baleen evolved thereafter, whereas another suggests that baleen evolved before teeth were lost. Here we report a new species of toothed mysticete, Coronodon havensteini, from the Oligocene of South Carolina that is transitional between raptorial archaeocete whales and modern mysticetes. Although the morphology and wear on its anterior teeth indicate that it captured large prey, its broad, imbricated, multi-cusped lower molars frame narrow slots that were likely used for filter feeding. Coronodon havensteini is a basal, if not the most basal, mysticete, and our analysis suggests that it is representative of an initial stage of mysticete evolution in which teeth were functional analogs to baleen. In later lineages, the diastema between teeth increased—in some cases, markedly so—and may mark a stage at which the balance of the oral fissure shifted from mostly teeth to mostly baleen. When placed in a phylogenetic context, our new taxon indicates that filter feeding was preceded by raptorial feeding and that suction feeding evolved separately within a clade removed from modern baleen whales.

Keywords: Mysticeti; filter feeding; baleen; oligocene; South Carolina; toothed mysticete

Systematics

Order Cetacea 

 Suborder Mysticeti 

Coronodon havensteini gen. et sp. nov.

Holotype: CCNHM 108. Nearly complete, 1.0-m-long skull, mandibles, 14 vertebrae, and partial ribs (Figures 1, 2, and 3; Figures S1–S3; Tables S1 and S2).

Etymology: Coronodon havensteini. Genus is Greek for “crown tooth,” referring to the multi-cusped molars. The species name recognizes Mark Havenstein, who discovered the holotype.

Locality and Age: Wando River near Highway 41 Bridge, South Carolina, Berkeley County. Ashley Formation, Oligocene, uppermost Rupelian. 

Diagnosis: Coronodon has the following mysticete synapomorphies: supraoccipital level with temporal fossa (character 25: state 1), broad basioccipital crests (39: 2), all cusps of posterior teeth subequal (99: 1), upturned antorbital process of maxilla (100: 1), and splayed basal cusps on posterior teeth (206: 1). Like some archaeocetes, its rostrum is twisted counterclockwise in anterior view (Figure 3). Coronodon havensteini is unique in having anterior lower molars labially overlapping posterior lower molars.  ....

Figure 1. Cranium and Upper Dentition of Coronodon havensteini sp. et gen. nov.
(A–E) Cranium in (A) lateral and (B) dorsal views. For comparison, (C) shows a dorsal view of the archaeocete Zygorhiza kochii (USNM 11962). Also shown of Coronodon are the left P3 in (D) labial and (E) lingual views. (F and G) Left M2 in (F) labial and (G) lingual views. (H and I) Right bulla in (H) dorsal view and left petrosal in (I) ventrolateral view. Portions in gray are reconstructed.

ap, anterior process of petrosal; cp, conical apophysis; fr, fenestra rotunda; Fr, frontal; lt, ventrolateral tuberosity; mf, fossa for malleus; Mx, maxilla; Na, nasal; ol, outer lip of bulla; os, occipital shield; Pa, parietal; pc, pars cochlearis; pbf, posterior facet for bulla; pgp, postglenoid process; pp, posterior process of bulla; Px, premaxilla; sp, sigmoid process; Sq, squamosal; sc, sagittal crest; Vo, vomer; zy, zygomatic process; VII canal for facial nerve. Scale bars in (A)–(C), 10 mm. Scale bars in (D)–(I), 5 mm. Blue denotes dental wear and red denotes dental erosion.

Coronodon havensteini  Geisler, Boessenecker, Brown & Beatty, 2017 

In this reconstruction, the two main whales in the center are Coronodon havensteini, the lower two in the background are Echovenator sandersi), and the birds in the sky are Pelagornis sandersi (false toothed birds with a wingspan near 6.5 m).

Illustration: Alberto Gennari  

Jonathan H. Geisler, Robert W. Boessenecker, Mace Brown and Brian L. Beatty. 2017. The Origin of Filter Feeding in Whales. Current Biology. In Press. DOI: 10.1016/j.cub.2017.06.003

 twitter.com/CoastalPaleo/status/880455087386132480

Ancient South Carolina whale yields secrets to filter feeding's origins 

phy.so/417944795 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 • 2017] The early Miocene Balaenid Morenocetus parvus from Patagonia (Argentina) and the Evolution of Right Whales ---ScRaBBlE

 Morenocetus parvus Cabrera, 1926

 Art by Jorge Gonzalez.

in Buono​, Fernández, Cozzuol, et al. 2017 

DOI:  10.7717/peerj.4148 

Abstract

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ∼20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length of Morenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene–early Pliocene as represented by Eubalaena shinshuensis.

Figure 13: Reconstructions of balaenid crania in left lateral view, showing relative position of the orbit and eyeball (in blue) with arching of the rostrum. (A) Morenocetus parvus. (B) Balaenella brachyrhynus. (C) Eubalaena australis. The rostrum in (B) is depicted as preserved in the original specimen.

Figure 15: Artistic restoration of Morenocetus parvus in life. 

Art by Jorge Gonzalez. 

Systematic palaeontology

Cetacea Brisson, 1762

Neoceti Fordyce & Muizon, 2001

Mysticeti Gray, 1864 sensu Cope, 1869

Chaeomysticeti Mitchell, 1989

Balaenidae Gray, 1825

Morenocetus Cabrera, 1926

Type species by monotypy: Morenocetus parvus Cabrera, 1926.

....

Mónica R. Buono​, Marta S. Fernández, Mario A. Cozzuol, José I. Cuitiño and Erich M.G. Fitzgerald. 2017. The early Miocene Balaenid Morenocetus parvus from Patagonia (Argentina) and the Evolution of Right Whales.  PeerJ. 5:e4148.  DOI:  10.7717/peerj.4148

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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 • 2017] Decoupling Tooth Loss from the Evolution of Baleen in Whales ---ScRaBBlE

Baleen whales, or mysticetes, include the largest vertebrates to have ever evolved. Their gigantism, evolutionary success, and ecological diversity have been linked to filter feeding. Mysticetes filter feed using elaborate keratinous baleen plates, which grow from the palate and allow them to strain large quantities of prey out of the water. While the earliest mysticetes retained the adult, mineralized teeth present in ancestral whales, all species of living baleen whales lack teeth and instead possess baleen. The mechanism by which this evolutionary transformation took place remains unknown. We present four independent, but non-exclusive hypotheses for the origin of baleen. We evaluate the support for these hypotheses based on separate lines of evidence, including paleontological, molecular, and ontogenetic data. We suggest that the origin of baleen is decoupled from the loss of teeth, with a separate morphological and genetic basis. Moreover, we outline how new fossils and phylogenetic analyses may resolve current debates about morphological transformations in tooth loss and baleen origin across the phylogeny of stem and crown Mysticeti. Additional insights will likely arise from more detailed examination of developmental and biomechanical data, with sufficient ontogenetic and phylogenetic sampling.

  Key Words: Cetacea, dentition, filter feeding, fossils, Mammalia, Mysticeti, teeth  

Figure 1: Four hypothetical transitional filter feeding stages in mysticetes, with oblique lateral views of a generalized stem mysticete. Hypotheses (A-D) are not mutually exclusive, nor explicitly step-wise.

See text for more details. All artwork courtesy Alex Boersma (http://www.alexboersma.com). 

Carlos Mauricio Peredo, Nicholas D. Pyenson and Alexandra T. Boersma. 2017. Decoupling Tooth Loss from the Evolution of Baleen in Whales. Front. Mar. Sci.  DOI:  fmars.2017.00067

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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] Maiabalaena nesbittae • Tooth Loss Precedes the Origin of Baleen in Whales ---ScRaBBlE

Maiabalaena nesbittae 

 Peredo, Pyenson, Marshall & Uhen, 2018

  DOI: 10.1016/j.cub.2018.10.047

 Illustration: Alex Boersma (AlexBoersma.com)

 twitter.com/CMPeredo

Highlights

• Maiabalaena nesbittae is 33 million year old fossil baleen whale from Oregon

• Maiabalaena has neither teeth, nor baleen

• Early whales lost teeth entirely before the evolutionary origin of baleen

• Despite no teeth or baleen, these whales were effective suction feeders

Summary

Whales use baleen, a novel integumentary structure, to filter feed; filter feeding itself evolved at least five times in tetrapod history but demonstrably only once in mammals. Living baleen whales (mysticetes) are born without teeth, but paleontological and embryological evidence demonstrate that they evolved from toothed ancestors that lacked baleen entirely. The mechanisms driving the origin of filter feeding in tetrapods remain obscure. Here we report Maiabalaena nesbittae gen. et sp. nov., a new fossil whale from early Oligocene rocks of Washington State, USA, lacking evidence of both teeth and baleen. The holotype possesses a nearly complete skull with ear bones, both mandibles, and associated postcrania. Phylogenetic analysis shows Maiabalaena as crownward of all toothed mysticetes, demonstrating that tooth loss preceded the evolution of baleen. The functional transition from teeth to baleen in mysticetes has remained enigmatic because baleen decays rapidly and leaves osteological correlates with unclear homology; the oldest direct evidence for fossil baleen is ∼25 million years younger than the oldest stem mysticetes (∼36 Ma). Previous hypotheses for the origin of baleen are inconsistent with the morphology and phylogenetic position of Maiabalaena. The absence of both teeth and baleen in Maiabalaena is consistent with recent evidence that the evolutionary loss of teeth and origin of baleen are decoupled evolutionary transformations, each with a separate morphological and genetic basis. Understanding these macroevolutionary patterns in baleen whales is akin to other macroevolutionary transformations in tetrapods such as scales to feathers in birds.

Keywords: baleen, cetacea, filter-feeding, mysticeti, suction feeding

Figure 1. Cranial Elements of the Holotype of Maiabalaena nesbittae, USNM 314627.

Systematics 

Cetacea; Pelagiceti; 

Neoceti; Mysticeti; 

Maiabalaena nesbittae gen. et sp. nov. 

Etymology: Maiabalaena combines Maia-, meaning mother, and -balaena, meaning whale. Named for its phylogenetic position as basal to baleen-bearing mysticetes. The specific epithet nesbittae honors Dr. Elizabeth A. Nesbitt for her lifetime of contribution to paleontology of the Pacific Northwest and her mentorship and collegiality at the Burke Museum of Natural History and Culture in Seattle, Washington, USA.

 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes:
 (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus.

These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

Figure 2. Phylogenetic Relationships of Stem Mysticetes Illustrating the Evolutionary Loss of Teeth and Subsequent Origin of Baleen Figure illustrates a composite phylogeny including results from this analysis (Figure S4) and recently published analyses.
(A) Time calibrated simplified phylogeny, with collapsed clade resolution for Mammalodontidae, Aetiocetidae and Eomysticetidae, and crown Mysticeti.
 (B–E) Colored bars indicate groups figured; gray bars indicate groups not figured. Panels (b–e) represent 3D models of select specimens in lateral view with artistic reconstructions of their feeding modes: (B) Basilosaurus isis; (C) Coronodon havensteini; (D) Maiabalaena nesbittae; and (E) Balaenoptera musculus. These panels illustrate the loss of a functional dentition, the intermediate phase with neither teeth nor baleen, and the subsequent origin of baleen. Illustrations are original artwork by Alex Boersma (www.alexboersma.com).

This is an artistic reconstruction of a mother and calf of Maiabalaena nesbittae nursing offshore of Oregon during the Oligocene, about 33 million years ago. While Maiabalaena would not have been able to chew or filter feed, muscle attachments on the bones of its throat indicate it likely had strong cheeks and a retractable tongue. These traits would have enabled it to suck water into its mouth, taking up fish and small squid in the process. The ability to suction feed would have rendered teeth, whose development requires a lot of energy to grow, unnecessary. The loss of teeth, then, appears to have set the evolutionary stage for the baleen, which the scientists estimate arose about 5 to 7 million years later.

 Illustration: Alex Boersma (www.alexboersma.com)

 Carlos Mauricio Peredo, Nicholas D. Pyenson, Christopher D. Marshall and Mark D. Uhen. 2018. Tooth Loss Precedes the Origin of Baleen in Whales. Current Biology.  DOI: 10.1016/j.cub.2018.10.047

 twitter.com/CMPeredo/status/1068179652135534592

 twitter.com/CMPeredo/status/1068229477375901696

 twitter.com/PyensonLab/status/1068215385613324290

twitter.com/NMNH/status/1068184159632453634

Whales Lost Their Teeth Before Evolving Hair-like Baleen in Their Mouths  si.edu/newsdesk/releases/whales-lost-their-teeth-evolving-hair-baleen-their-mouths via @Smithsonian

Toothless, 33-Million-Year-Old Whale Could Be an Evolutionary ‘Missing Link’  gizmodo.com/toothless-33-million-year-old-whale-could-be-an-evolut-1830739126 via @gizmodo

    

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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] Toipahautea waitaki • A New Archaic Baleen Whale (early-Late Oligocene, New Zealand) and the Origins of Crown Mysticeti ---ScRaBBlE

Toipahautea waitaki   Tsai & Fordyce, 2018

Burial in the ancient sea of Zealandia: a Toipahautea whale skeleton is slowly covered by sand 27-28 million years ago, on its path to becoming a fossil 

 Reconstruction by Chris Gaskin, Geology Museum, University of Otago 

DOI: 10.1098/rsos.172453

A new genus and species of extinct baleen whale, †Toipahautea waitaki (Late Oligocene, New Zealand) is based on a skull and associated bones, from the lower Kokoamu Greensand, about 27.5 Ma (local upper Whaingaroan Stage, early Chattian). The upper jaw includes a thin, elongate and apparently toothless maxilla, with evidence of arterial supply for baleen. Open sutures with the premaxilla suggest a flexible (kinetic) upper jaw. The blowhole is well forward. The mandible is bowed laterally and slightly dorsally; unlike the Eomysticetidae, there are no mandibular alveoli, and the coronoid process is tapered and curved laterally. Jaw structure is consistent with baleen-assisted gulp-feeding. The age of early Chattian makes †Toipahautea a very early, if not the oldest named, toothless and baleen-bearing mysticete, suggesting that the full transition from toothed to baleen-bearing probably occurred in the Early Oligocene. Late Oligocene mysticetes vary considerably in jaw form and kinesis, tooth form and function, and development of baleen, implying a wide range of raptorial, suctorial and filter-feeding behaviour. More study may elucidate the function of jaws, teeth and baleen in terms of opportunist/generalist feeding, as in modern gray whales, versus specialized feeding. We here propose that early mysticetes, when transitioned from toothed to baleen-bearing, were generalists and opportunists instead of specializing in any forms of feeding strategies. In addition, two different phylogenetic analyses placed †Toipahautea either in a polytomy including crown Mysticeti, or immediately basal to the crown, and above †Eomysticetidae in both cases. Because the †Toipahautea waitaki holotype is an immature individual, it may plot more basally in phylogeny than its true position.

Keywords:Cetacea, mysticete, feeding strategy, filter-feeding, specialist/generalist, opportunist

  initial preparation of †Toipahautea waitaki OU 21981 by A. Grebneff

 (photo: R.E. Fordyce)

Burial in the ancient sea of Zealandia: a Toipahautea whale skeleton is slowly covered by sand 27-28 million years ago, on its path to becoming a fossil

 Reconstruction by Chris Gaskin, Geology Museum, University of Otago 

Cetacea Brisson, 1762
Mysticeti Gray, 1864

Incertae familiae

Toipahautea waitaki gen. et. sp. nov 

Etymology. Toi means origin and pahautea refers to whalebone/baleen in Maori, alluding to the origin of the early toothless and baleen-bearing mysticetes. Waitaki is a name for the wider region, including the Waitaki River (wai, water or river; taki, tears) into which the smaller Hakataramea River drains.

 Holotype. †Toipahautea waitaki is known only from the holotype, OU 21981: a disarticulated partial skull (parts of the maxillae and premaxillae, left nasal, frontals, squamosals, exoccipitals, basioccipital and supraoccipital), incomplete mandibles, left tympanic bulla and periotic, hyoid(?), atlas, axis, two thoracic vertebrae, two scapulae, a partial humerus, two radii and ribs. Most of the elements were disarticulated but associated when excavated.

Diagnosis. †Toipahautea waitaki is interpreted as a chaeomysticete based on the presence of ‘baleen’ sulci on the ventral surface of the maxilla and lack of mandibular alveoli. †Toipahautea waitaki has a unique combination of: massive size of periotic; well-developed superior process of the periotic; prominent elongation of dorsomedial margin of the internal acoustic meatus; prominent fissure between the fenestra rotunda and the aperture for the cochlear aqueduct; small medial posterior sulcus; the presence of the anteroexternal foramen; the presence of the sigmoidal cavity; the presence of the elliptical foramen; horizontal sigmoidal cleft far anterior than the anterior margin of the sigmoidal process; posteromedial margin of the bulla orienting slightly anteromedially.

Locality and horizon. OU 21981 (field number REF-28.1.88.2) was recovered from the Hakataramea Valley, South Canterbury, South Island, New Zealand (figure 1). ....

....

Cheng-Hsiu Tsai and R. Ewan Fordyce. 2018. A New Archaic Baleen Whale,Toipahautea waitaki (early-Late Oligocene, New Zealand) and the Origins of Crown Mysticeti.   R. Soc. Open Sci. 5: 172453.  DOI: 10.1098/rsos.172453

Whale of a find  odt.co.nz/news/national/whale-find

 scimex.org/newsfeed/oldest-baleen-whale-uncovered-in-new-zealand

 scimex.org/__data/assets/file/0016/316132/Baleen-whale_RSOS_paper.pdf

Whale of a discovery: NZ's ancient (and extinct) ocean mammal, via @nzherald nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=12034869

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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.