Author Archives: LS

New Captorhinid Reptile Found in China

A new captorhinid reptile, Gansurhinus qingtoushanensis, gen. et sp. nov., was found from Xidagou Formation (Middle Permian) at Qingtoushan (Dashankou) locality near Yumen, Gansu Province, and from Naobaogou Formation (Late Permian) in Baotou, Nei Mongol, China, as reported in the recent issue of Naturwissenschaften 98 (435–441), 2011. The find provides new evidence for further studies on the evoluting and paleogeography of captorhinid reptiles.

http://english.ivpp.cas.cn/rh/rp/201105/t20110523_70125.html

—
Majid

Brain evolution and other Mesozoic mammal stuff

Some new meso-mammal-papers picked up from Dinosaur Discussion List… 🙂

–Mikko H.

Some recent items about Mesozoic mammals.

In the new issue of Science:

R. Glenn Northcutt (2011)
Perspective Paleontology: Evolving Large and Complex Brains.
Science 332 (6032): 926-927 (20 May 2011):
DOI: 10.1126/science.1206915
http://www.sciencemag.org/content/332/6032/926.summary

Summary
During the Mesozoic (∼250 million to 65 million years ago), two
distantly related groups of reptiles-the cynodont (or mammal-like) reptiles
and the coelurosaurian theropod dinosaurs-gave rise to mammals and birds,
respectively. Both mammals and birds evolved brains some 10 times as large,
relative to a given body weight, as those of their ancestors (1). In both
groups, these brains contributed to the evolution of the ability to control
body temperature (endothermy) and complex social interactions, including
parental care and a reliance on learning that even involves tool use (2,
3). The size of most parts of the brain increased in birds and mammals, but
the cerebral hemispheres and cerebellum, both of which are involved in
sensory and motor integration, underwent particularly spectacular
development (see the figure). Although mammals and birds evolved from
distantly related groups of reptiles, the higher integrative centers and
circuitry of their cerebral hemispheres are very similar, and comparative
neurobiologists continue to vigorously debate whether these centers evolved
from the same ancestral neural centers (4, 5) or from different ones (6-8).
Speculation about the evolutionary steps leading to large and complex
mammalian and avian brains is equally contentious and unresolved, in part
because of the rarity of fossil skulls and, until recently, the need to
destroy such skulls in order to expose the endocasts (casts molded by the
cranial cavity). Typically, endocasts are the only record of the brain’s
outward appearance in a transitional form, because brains themselves are
rarely fossilized.

Timothy B. Rowe, Thomas E. Macrini, and Zhe-Xi Luo (2011)
Fossil Evidence on Origin of the Mammalian Brain.
Science 332(6032): 955-957 (20 May 2011):
DOI: 10.1126/science.1203117
http://www.sciencemag.org/content/332/6032/955.abstract

Abstract
Many hypotheses have been postulated regarding the early evolution of the
mammalian brain. Here, x-ray tomography of the Early Jurassic mammaliaforms
Morganucodon and Hadrocodium sheds light on this history. We found that
relative brain size expanded to mammalian levels, with enlarged olfactory
bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two
evolutionary pulses. The initial pulse was probably driven by increased
resolution in olfaction and improvements in tactile sensitivity (from body
hair) and neuromuscular coordination. A second pulse of olfactory
enhancement then enlarged the brain to mammalian levels. The origin of
crown Mammalia saw a third pulse of olfactory enhancement, with ossified
ethmoid turbinals supporting an expansive olfactory epithelium in the nasal
cavity, allowing full expression of a huge odorant receptor genome.

J. David Archibald, Yue Zhang, Tony Harper and Richard L. Cifelli (2011)
Protungulatum, Confirmed Cretaceous Occurrence of an Otherwise Paleocene
Eutherian (Placental?) Mammal.
Journal of Mammalian Evolution (advance online publication)
DOI: 10.1007/s10914-011-9162-1
http://www.springerlink.com/content/n661405803q511n8/

Neither pre-Cenozoic crown eutherian mammals (placentals) nor archaic
ungulates (“condylarths”) are known with certainty based on the fossil
record. Herein we report a new species of the Paleocene archaic ungulate
(“condylarth”) Protungulatum from undisputed Late Cretaceous aged rocks in
Montana USA based on an isolated last upper premolar, indicating rare
representatives of these common early Tertiary mammals appeared in North
America a minimum of 300 k  years before the extinction of non-avian
dinosaurs. The other 1200 mammal specimens from the locality are
characteristic Late Cretaceous taxa. This discovery overturns the current
hypothesis that archaic ungulates did not appear in North America until
after the Cretaceous/Tertiary (K/T) boundary and also suggests that other
reports of North American Late Cretaceous archaic ungulates may be correct.
Recent studies, including ours, cannot determine whether Protungulatum does
or does not belong to the crown clade Placentalia.

A few months old but its free–pdf of short survey article about Chinese
Mesozoic mammals:
http://english.ivpp.cas.cn/rh/as/201012/P020101207396650166902.pdf

A. O. Averianov and A. V. Lopatin (2011)
Phylogeny of triconodonts and symmetrodonts and the origin of extant
mammals.
Doklady Biological Sciences 436(1): 32-35,
DOI: 10.1134/S0012496611010042
http://www.springerlink.com/content/3x027744038g6866/
(no abstract)

Canine Tooth from Peking Man Identified in Sweden!

Paleontologists from Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, and Swedish colleagues from Uppsala University, recently identified a unique canine tooth from Peking Man among the contents of the 40 cartons left unopened and forgotten at the Museum of Evolution at Swedish Uppsala University.

“The tooth has not been touched since it was dug up in the 1920s in China. We and our Chinese colleagues are overwhelmed. With today’s technology, a canine tooth that has not been handled can tell us so much more than in the past, such as what they ate,” said Per Ahlberg, professor of evolutionary developmental biology at Uppsala University.

Fossils from well-known Peking man are extremely rare, as most of the finds disappeared during World War II. All that remains in China today are five teeth and a few pieces of skull bone that were found in the 1950s and 1960s.

Swedish paleontologists were the first group of scientists to go to China in the early 20th century to carry out a series of expeditions in collaboration with Chinese colleagues. They found large numbers of fossils of dinosaurs and other vertebrates. The material was sent to Sweden and the well-known paleontologist Carl Wiman identified and described the fossils. But when the policy of research changed after Wiman’s death, 40 cartons were left unopened and forgotten. Just a few weeks ago, Ahlberg and his colleague Martin Kundrat, and Museum Director Jan Ove Ebbestad noticed the cartons in a museum storeroom. They have gone through the material and contacted Drs. LIU Wu and TONG Haowen, from the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, who were excited and flew to Sweden to confirm the identification of the tooth.

“This is an extremely important find. It is the only canine tooth in existence. It can yield important information about how Homo erectus lived in China,” said LIU Wu.

The Museum of Evolution kept the best collection of Chinese fossils of dinosaurs and other vertebrates outside of China, and the contents of the 40 cartons further enhance the value of the collection. The fossil material comes from several different areas in China. For example, specimens from Zhoukoudian, southwest of Beijing, were made of skulls and other skeletal parts, including this canine tooth from Homo erectus or Peking man.

—
Majid

Toothache in Permian reptile

In popular news:

http://news.discovery.com/animals/ancient-reptile-toothache-110418.html

The actual paper:

Osteomyelitis in a Paleozoic reptile: ancient evidence for bacterial infection and its evolutionary significance

Robert R. Reisz & Diane M. Scott & Bruce R. Pynn & Sean P. Modesto, Naturwissenschaften DOI 10.1007/s00114-011-0792-1

We report on dental and mandibular pathology in Labidosaurus hamatus, a 275 million-year-old terrestrial reptile from North America and associate it with bacterial infection in an organism that is characterized by reduced tooth replacement. Analysis of the surface and internal mandibular structure using mechanical and CT-scanning techniques permits the reconstruction of events that led to the pathology and the possible death of the individual. The infection probably occurred as a result of prolonged exposure of the dental pulp cavity to oral bacteria, and this exposure was caused by injury to the tooth in an animal that is characterized by reduced tooth replacement cycles. In these early reptiles, the reduction in tooth replacement is an evolutionary innovation associated with strong implantation and increased oral processing. The dental abscess observed in L. hamatus, the oldest known infection in a terrestrial vertebrate, provides clear evidence of the ancient associa- tion between terrestrial vertebrates and their oral bacteria.

-Laura

Definitive* proof of multiple origins of Definitive Mammalian Middle Ear (DMME)

A very nice paper and ‘News and Views’ on the discovery of yet another incredibly well preserved early mammal from Liaoning, China. This one preserved both ossified Meckels cartilage (OMC, already known from close relatives) AND attached to this are ALL of the middle ear bones! These are adrift of the dentary where they are thought to have moved from into the ear of mammals, yet they are still attached to it via this OMC. As the new beastie is found ‘higher’ up the phylogenetic tree than monotremes and multituberculates, both known to have the DMME, and plenty of close and distant relatives have either the OMC or a groove where it is thought the OMC lies, it indicates that the DMME, once thought to indicate the origin of mammalia, has likely evolved multiple times independently:

http://www.nature.com/nature/journal/v472/n7342/full/nature09921.html

and News and Views on the paper:

http://www.nature.com/nature/journal/v472/n7342/full/472174a.html

* This is ‘definitive’ if you accept a) the phylogeny presented and b) that this is not simply a reversal (though the presence of the ossified meckels cartilage in multiple taxa indicates this is unlikely). The phylogeny is open to discussion however, as it is partly based on the hypothesis that tribosphenic teeth also evolved independently at least twice, and there is evidence both for and against this. If you accept both of these, it’s homoplasy a go go in the two key mammalian morphological key innovations!

-Ian

3D Neanderthal comes to a screen near you

Ever wondered what Neanderthals looked like? Or how they walked? Well wonder no more with the London Natural History Museum website’s new augmented reality (AR) Neanderthal.

All you need is a printer and a webcam to see a 3D Neanderthal walk about on your desk, and stop for a stretch, through your computer screen.

http://www.nhm.ac.uk/about-us/news/2011/february/3d-neanderthal-comes-to-a-screen-near-you94923.html

__________________________________
Laura K. Säilä, PhD

Giant (Easter) bunny found!

The Easter bunny came early this year for a few scientists working on the Spanish island of Minorca.

The team has just announced the discovery of Earth’s biggest known rabbit species, an oddly unbunny-like giant dubbed Nuralagus rex—”the Minorcan king of the hares.”The 26-pound (12-kilogram) prehistoric species was about six times bigger than the common European rabbit, found on most continents, according to an analysis of several bones. The newfound rabbit’s “roly-poly, tanklike” appearance and weird anatomy may have arisen because of its stress-free lifestyle.

http://news.nationalgeographic.com/news/2011/03/110323-giant-rabbit-minorca-biggest-bunny-science-nuralagus-rex-largest/
http://www.vertpaleo.org/source/blog/post.cfm/press-release-giant-extinct-rabbit-was-the-king-of-minorca

__________________________________
Laura K. Säilä, PhD

Chinese Paleontologist Raise Doubts About a Cheetah Fossil

In a 24 December 2010 News Focus story in Science, Dr. DENG Tao,  Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Chinese Academy of Sciences, presented a query for a 2009 PNAS paper by Per Christiansen of the Zoological Museum in Copenhagen and Ji H. Mazák of the Shanghai Science and Technology Museum. Christiansen and Mazák reported a new species of the cheetah (Acinonyx kurteni) from the Late Pliocene loess deposits of the Linxia Basin in Gansu Province, China. As a vertebrate paleontologist who specialized on the Late Cenozoic mammals of the Linxia Basin for many years, Deng naturally had particular interests in reading this paper. Having carefully checked the described skull in this paper’s figures, unfortunately, he found that Christiansen and Mazák studied a fossil forgery, the sole foundation of the paper. In a 4 March 2011 letter in Science, Mazák and Christiansen note “the occipital area and zygomatic arches have been heavily restored in plaster, probably to make it appear more complete, thus enhancing its commercial value, a common malpractice among Chinese fossil dealers.” Deng and his colleague responded, also in Science, that they are pleased to see this note, but stand by their view that the skull is a composite with fabricated features.

Read more at: http://english.ivpp.cas.cn/ns/es/201103/t20110304_65943.html

– Majid

Newsflash: Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals

Diversity and evolution of Hunter-Schreger Band configuration in tooth enamel of perissodactyl mammals

Wighart Von Koenigswald, Luke T. Holbrook, and Kenneth D. Rose

Acta Palaeontologica Polonica 56 (1), 2011: 11-32 doi:10.4202/app.2010.0021

Four different Hunter−Schreger Band (HSB) configurations were observed in the teeth of fossil and extant Perissodactyla. This variability exceeds that observed in Artiodactyla or Proboscidea. The four HSB configurations represent two different evolutionary pathways. Transverse HSB found in many mammalian taxa outside the Perissodactyla represents the most primitive HSB configuration. It occurs in several primitive perissodactyl families and is retained in Palaeotheriidae and extant Equidae. Curved HSB evolved from transverse HSB and occurs in Tapiridae, Helaletidae, and Lophiodontidae, as well as in Ancylopoda and Titanotheriomorpha. This likely indicates independent evolution of curved HSB in two or more lineages, but the number of instances of parallelism of this configuration is obscured by uncertainty in the relationships among these taxa and by a lack of data for some important basal taxa. A second evolutionary pathway leads from transverse HSB via compound HSB to vertical HSB. Compound HSB were detected in Hyrachyidae, Deperetellidae, and the early rhinocerotid Uintaceras. Vertical HSB configuration characterizes the molar dentition of other Rhinocerotidae, Hyracodontidae, Indricotheriidae, andAmynodontidae. Often, the incisors of rhinocerotids retain traces of compound HSB. Thus theHSB configuration reflects phylogenetic relationships to some degree. The selective value of themodified HSB configurations is interpreted functionally as amechanismto reduce abrasion duringmastication, assuming that the perpendicular intersection of prismswith the actual grinding surfaces resists wear better than prisms running parallel to the occlusal surface.

-Mikko