Kolponomos Basics

[brobear]

From site given in reply #20.
                                                     

[King Kodiak]

I was wondering what was the relationship between Kolponomos and other animals, the interactions. We dont have data on this. All we know is that it was a marine predator.

[brobear]

Dec 24, 2019 14:55:04 GMT -5 King Kodiak said:

I was wondering what was the relationship between Kolponomos and other animals, the interactions. We dont have data on this. All we know is that it was a marine predator.

Quote from reply #14: Large neck muscle attachments and robust foot bones combine with these features to suggest that Kolponomos filled a unique niche among marine carnivores, approached today only by the unrelated sea otter. 
 
We know that Kolponomos was closely related to bears and lived a lifestyle similar to the sea otter. Not likely an aggressive animal as it fed on shellfish ( clams, oysters, etc. ).

[OldGreenGrolar]

Bull walruses can be aggressive despite feeding mainly on shellfish and clams (old bulls occasionally sionally turn carnivorous). Therefore, the kolpomonos aggression can’t be determined by its diet alone.

[brobear]

Dec 25, 2019 7:04:58 GMT -5 OldGreenGrolar said:

Bull walruses can be aggressive despite feeding mainly on shellfish and clams (old bulls occasionally sionally turn carnivorous). Therefore, the kolpomonos aggression can’t be determined by its diet alone.

The walrus is defensively aggressive... as is a cornered rat. But you're right; considering that the three most dangerous ( vertebrate ) animals in Africa are all vegetarians - hippo, elephant, and Cape buffalo, we cannot gauge aggression on diet.

[brobear]

en.wikipedia.org/wiki/Kolponomos

Kolponomos is an extinct genus of carnivoran mammal that existed in the Late Arikareean North American Land Mammal Age, early Miocene epoch, about 20 million years ago. It was likely a marine mammal. The genus was erected in 1960 by Ruben A. Stirton, a paleontologist at the University of California Museum of Paleontology, Berkeley, for the species K. clallamensis, on the basis of a partial skull and jaw found on the Olympic Peninsula. At the time, Stirton questionably assigned it to Procyonidae, its systematic position remained problematic until the discovery of more fossils including a nearly complete cranium from the original locality of K. clallamensis which helped identify it as part of the group from which pinnipeds evolved.

In life, species of Kolponomos had downturned snouts and broad, heavy molars that would have been suited to a diet of hard-shelled marine invertebrates, and their narrow snouts and anteriorly directed eyes indicate that they would have had stereoscopic vision. Large neck muscle attachments and robust foot bones combine with these features to suggest that Kolponomos filled a unique niche among marine carnivores, approached today only by the very distantly related sea otter. Due to the lack of a complete skeleton, however, it is difficult to make inferences about this genus' other adaptations.

Based on the skull and jaws known, Kolponomos convergently evolved mandibular and bite features that had similarities to extant bears, sea otters, and even the sabretooth Smilodon. The anterior portion of the jaw becomes a functional anchoring fulcrum in both Kolponomos and Smilodon. Although dental morphology and heavy occlusal wear patterns are shared with the sea otter. Kolponomos' dentition was less efficient but exhibited higher stiffness than in the sea otter. Brian Switek wrote that Kolponomos bit like a sabrecat, crunched like a bear.

Aspects of its feeding morphology were similar to the giant otter Siamogale melilutra, although Kolponomos is not an otter.

Kolponomos clallamensis is known from the Miocene of Slip Point Lighthouse, Washington (48.3°N 124.2°W, paleocoordinates 48.0°N 116.9°W). The species was originally based on a rostrum found in 1957 at Slip Point in Clallam Bay, Washington. A nearly complete cranium was found at the same location in 1988. Both K. clallamensis and K. newportensis are associated with the late Arikareean NALMA.

Kolponomos newportensis was described in 1994 by R. Tedford, L. Barnes and Clayton E. Ray. It is represented by single specimen: a nearly complete skull, jaw and post-cranial bones found in a concretion of sediment. The concretion was discovered in two pieces by fossil collector Douglas Emlong near Newport, Oregon, the first in 1969 and the second, eight years later, in 1977. Because the concretion had been hardened so much by tectonic stress, the paleontological laboratory at the Smithsonian Institution considered them "the most difficult materials ever encountered by our laboratory.," and a combination of techniques proved essential to its extraction and preparation, which lasted two decades. Discovery of K. newportensis disproved the earlier hypothesis that the genus was related to ancestors of raccoons, and showed instead that it is an early but unusual bear relative closely tied to the origin of pinnipeds.
    
   

[King Kodiak]

A unique feeding strategy of the extinct marine mammal Kolponomos: convergence on sabretooths and sea otters


Mammalian molluscivores feed mainly by shell-crushing or suction-feeding. The extinct marine arctoid, Kolponomos, has been interpreted as an otter-like shell-crusher based on similar dentitions. However, neither the masticatory biomechanics of the shell-crushing adaptation nor the way Kolponomos may have captured hard-shelled prey have been tested. Based on mandibular symphyseal morphology shared by Kolponomos and sabre-toothed carnivores, we hypothesize a sabretooth-like mechanism for Kolponomos prey-capture, whereby the mandible functioned as an anchor. Torque generated from jaw closure and head flexion was used to dislodge prey by prying, with prey then crushed using cheek teeth. We test this hypothesized feeding sequence using phylogenetically informed biomechanical simulations and shape analyses, and find a strongly supported, shared high mandibular stiffness in simulated prey-capture bites and mandibular shape in Kolponomos and the sabre-toothed cat Smilodon. These two distantly related taxa converged on using mandibles to anchor cranial torqueing forces when prying substrate-bound prey in the former and sabre-driving forces during prey-killing in the latter. Simulated prey-crushing bites indicate that Kolponomos and sea otters exhibit alternative structural stiffness-bite efficiency combinations in mandibular biomechanical adaptation for shell-crushing. This unique feeding system of Kolponomos exemplifies a mosaic of form-function convergence relative to other Carnivora.


.. Kolponomos is known by two species from the Miocene of Washington and Oregon (Tedford et al. 1994) and skull fragments from Alaska ( Jacobs et al. 2009). Kolponomos had a massive skull with a markedly downturned snout, binocular vision, and broad, crushing teeth suited to a diet of hard-shelled marine invertebrates such as crabs or clams; invertebrates were pried or twisted off rocks using enlarged caniniform teeth and powerful neck muscles ( Tedford et al. 1994, Tseng et al. 2016). Further research is needed to determine what fossil arctoids are the closest relatives to pinnipeds and how the above taxa fit into the story of pinniped evolution since most have not yet been included in comprehensive phylogenetic data sets. ...


Despite lacking flipper-like manus and pes, shortened tail, and postdating the earliest Enaliarctos by nearly 10 my, this taxon exhibits several craniodental features unique to pinnipedimorphs includ- ing a posteriorly expanded hard palate, an enlarged infra- orbital foramen, a shelf-like p4 protocone, and a reduced and lingually positioned m2; cladistic analysis supported Puijila and the anatomically similar Potamotherium val- letoni (Oligo-Miocene, France and Germany) as sister to Enaliarctos (Rybczynski et al. 2009). If these relationships are borne out by future cladistic study, it is important to note that most of these features are also present in the enig- matic amphicynodontid Kolponomos (except shelf-like p4 protocone; Tedford et al. 1994), a bear-like molluskivore with enlarged sea otter-like cheek teeth, binocular vision, and ad- aptations for high bite force convergent with sabretooth cats ( Tedford et al. 1994;Tseng et al. 2016). Like the nonmarine otter-like Potamotherium and Puijila, initial cladistic anal- ysis identified Kolponomos as the possible sister taxon to Pinnipedimorpha (Tedford et al. 1994). ...


www.researchgate.net/publication/296644806_A_unique_feeding_strategy_of_the_extinct_marine_mammal_Kolponomos_convergence_on_sabretooths_and_sea_otters

[brobear]

Artwork:
             

[OldGreenGrolar]

The kolpomonos in that picture above has a little shoulder hump.

[OldGreenGrolar]

[King Kodiak]

Reply #30, very interesting that it says that Kolponomos had massive neck muscles even larger than today's bears.

[OldGreenGrolar]

It seems the kolpomonos might have the strongest neck of any bear pound to pound. I am not sure about its pound to pound strength overall but I think it at least exceeds that of the black bears.

[brobear]

royalsocietypublishing.org/doi/10.1098/rspb.2016.0044

Much more info on-site.
6. Summary and conclusions:
Based on the anteroventrally extended and hypertrophied mastoid processes and vertically oriented and deepened mandibular symphyses shared by sabre-toothed mammals and Kolponomos, combined with the sea otter-like cheek tooth morphology in Kolponomos, we proposed and tested a unique prey-capture–mastication sequence in the feeding apparatus of this extinct marine arctoid carnivoran. This distinctive feeding sequence involved first using the mandible as an anchor for torque application, created by powerful neck musculature acting through the cranium, to dislodge hard-shelled invertebrates attached to rocky substrates. FE simulation and GM results test, and support, this model by demonstrating extensive similarities between Kolponomos and Smilodon in high mandibular stiffness during prey-capture simulations and in mandibular shape, and their distinctions from more closely related caniform (otters, wolf, and brown bear) or feliform (leopard) carnivorans, respectively. The findings support our interpretation of the anterior portion of the jaw as a functional anchoring fulcrum in both Kolponomos and Smilodon during prey-capture, for prying in the former and stabilizing the canine shear-bite in the latter.

In addition, FE analyses show that, even if the mandible of Kolponomos shares similar dental morphology and heavy occlusal wear patterns with the sea otter, they do not share similarly stiff mandibles in unilateral crushing bite simulations. Instead, Kolponomos exhibits high stiffness and low efficiency, whereas sea otters exhibit lower stiffness and higher efficiency. The much stiffer mandible in Kolponomos resembles bears (and Smilodon, to a lesser extent) and is unlike otters or the other sampled carnivorans, and may indicate shell-crushing adaptation via a different combination of mandibular stiffness-efficiency, representing a trade-off in these biomechanical attributes compared with extant sea otters. Taken together, these data support a unique feeding repertoire in Kolponomos that does not have a close analogue in species in modern ecosystems. They also highlight how prey-capture strategies across vastly different environments and taxa nevertheless may be based on fundamentally similar biomechanical requirements for mandibular function, as in the marine molluscivore Kolponomos and hypercarnivorous terrestrial sabretooth predators such as Smilodon. Lastly, these findings also demonstrate a mosaic functional convergence in the mandible of Kolponomos within the prey-capture–mastication sequence: an initial phase of prey-capture resembling the canine shear-bite model of sabretooths, and sea otter-like dental wear and morphology but with structural stiffness emphasized over ME.
                                                                                                                              

[brobear]

en.wikipedia.org/wiki/Amphicynodontinae

Amphicynodontinae.

Amphicynodontinae is a probable clade of extinct arctoids. While some researchers consider this group to be an extinct subfamily of bears, a variety of morphological evidence links amphicynodontines with pinnipeds, as the group were semi-aquatic otter-like mammals. In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular analyses support bears being the closest living relatives to pinnipeds. According to McKenna and Bell (1997) Amphicynodontinae are classified as stem-pinnipeds in the superfamily Phocoidea. Fossils of these mammals have been found in Europe, North America and Asia. Amphicynodontines should not be confused with Amphicyonids (bear-dogs), a separate family of Carnivora which is a sister clade to arctoids within the caniforms, but which may be listed as a clade of extinct arctoids in older publications.

[brobear]

Atlas of prehistoric mammals. Paleoart by Oleg Martsun.
DetSmcuedpmbfoeourgns eodaormdi1r, f20ef1d9a · 21. Kolponomos (Kolponomos newportensis) North America. Miocene. Length -1,2 m, height - up to 1 m, weight - up to 100 kg ( 220.5 pounds )
                                

[OldGreenGrolar]

Up to 100 kgs. That is about the same weight as an average male jaguar.

[brobear]

Dec 15, 2020 4:38:31 GMT -5 OldGreenGrolar said:

Up to 100 kgs. That is about the same weight as an average male jaguar.

Yes; or the size of a typical black bear.    
 
220 pounds.

[OldGreenGrolar]

This is the only picture of the kolpomonos skeleton structure I can find (top left).

[brobear]

WORLD OF PREHISTORIC CREATURES

Kolponomos, a genus of marine bear from early Miocene North America.
It was about 1.2 m. ( 3 feet 11 inches ) long and stood 0.7 m. ( 2 feet 4 inches ) tall. 
by Lucas Lima
                    

[Montezuma]

I want wished that this bear was one of the largest prehistoric bears because i really likes its formidable face and its a unique type of bear. I wished that i measure 5 ft shoulder height, 10 ft body length and 2000 pounds weight.