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Topic: Yunnanozoon

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In the News (Mon 23 Apr 18)

 Yunnanozoon - Wikipedia, the free encyclopedia
The Yunnanozoon is a suspected chordate or hemichordate from the Lower Cambrian, Chengjiang biota of Yunnan province, China.
Yunnanozoon is similar to the form Haikouella, which is almost certainly a vertebrate.
A close relationship between Yunnanozoon and the phylum Vetulicolia has also been proposed.
en.wikipedia.org /wiki/Yunnanozoon   (197 words)

 Report of GeoScience Research Center: Vol.1
Yunnanozoon is the oldest known example of a hemichordate.
The phylum (or 'supergroup') Hemichordata is closely associated with the phylum Chordata, which includes the vertebrates along with other groups such as cephalochordates and urochordates.
The identification of Yunnanozoon is therefore also significant for the early evolution of chordates and vertebrates.
www.gs-rc.org /repo/repoe.htm   (417 words)

It is similar to the form Yunnanozoon[?] which is almost somewhat more primitive and is possibly a hemichordate.
There are anatomical differences from Yunnanozoon including a larger stomach, and smaller (0.1mm) pharyngeal teeth.
Haikouella does not have bones or a movable jaw, but it otherwise resembles vertebrates.
www.ebroadcast.com.au /lookup/encyclopedia/ha/Haikouella.html   (215 words)

 Duffy: Chordate Origins
Even the most widely accepted earliest chordate, Pikaia gracilens, from the Middle Cambrian Burgess Shale, was originally interpreted as a polychaete annelid (Walcott, 1911), but has since been allied with the cephalochordates based on synapomorphies such as chevron shaped myomeres and an anteriorly extending notochord (Conway Morris, 1998).
Although the preservation of the Yunnanozoon specimen reported in the focal paper is exceptional, at various points it has been interpreted as a segmented worm, a hemichordate and (here) as a cephalochordate.
It seems clear that the latter hypothesis is open to interpretation unless and until more examples of this specimen are found.
www.biology.ualberta.ca /courses.hp/biol606/OldLecs/Lecture2K.08.Duffy.html   (971 words)

 Dzik publications
There are several anatomical traits shared by the most primitive Early Cambrian chordates Yunnanozoon, the Middle Cambrian probable westergaardodinid Odontogriphus, and the Vendian problematicum Dickinsonia, and their body plans resemble that of the nemerteans.
The rhynchocoel of the nemerteans and (at least) the most anterior dorsal chamber of Dickinsonia may appear thus homologous, which is consistent with the idea of its homology with the notochord and myocoel of the chordates.
Dickinsonia, Odontogriphus, Yunnanozoon, and Pikaia may thus represent a developmental series, from muscular dorsal chambers to the organization of myomeres typical for all later chordates (Fig.
www.paleo.pan.pl /people/Dzik/Dzik2000a.htm   (658 words)

The earliest is Yunnanozoon lividum from the Early Cambrian, 525 Ma (= million years ago), of China.
Uniquely, the notochord of cephalochordates extends to the tip of the snout, the gonads are segmentally organized, adults have a high number (50+) gill arches, and there is a hood-like atrium covering the pharyngeal region.
The Early Cambrian fossil Yunnanozoon possesses the extended notochord and segmental gonads, but lack the atrium and increased number of gill arches.
tolweb.org /tree?group=Chordata&contgroup=Animals   (1676 words)

 Yannanozoon lividum
Description: This fine fossil is Yunnanozoon lividum, has been designated as the earliest known hemichordate.
Yunnanozoon was thought to be a member of the Phylum Chordata, but has been reassigned as mentioned above.
This is a most unusual association slab, and represents only the second example of Yunnanozoon I have been able to secure.
www.fossilmall.com /EDCOPE_Enterprises/Chengjiang/chengjiangfossils21/Chengjiangfossils-21.htm   (400 words)

 Introduction to the Cephalochordata   (Site not responding. Last check: 2007-09-10)
The famous Middle Cambrian Burgess Shale of British Columbia has yielded a few fossils of Pikaia, which appears to be a cephalochordate (although the fossils are still being restudied).
More recently, Yunnanozoon, from the Early Cambrian of south China, was reported to be a cephalochordate, the earliest known (Chen et al., 1995).
These fossils show that the chordate lineage appeared very early in the known history of the animal kingdom, and they strengthen the case for an origin of true vertebrates from a cephalochordate-like ancestor.
www.ucmp.berkeley.edu /chordata/cephalo.html   (558 words)

It seem that these were muscular chambers with a thin envelope of the basement membrane, filled with a fluid or fluid-rich tissue.
Only the pattern of character evolution through the vertebrate stem can reveal the true picture, but this is confused by preservational biases and difficulties inherent in assigning fossils to the stems of clades with deep divergence times.
Yunnanozoon and Haikouella have no eyes and brain (Shu and Conway Morris 2003) and even a notochord (Valentine 2004).
rocek.gli.cas.cz /hatschek_soubory/abstracts.htm   (6032 words)

 Department of Biology - Appalachian State University
Thus morphological complexity originated early in the evolution of Metazoa, and macroscopic and modularized organisms may have characterized the fauna populating the Vendian oceans long before the appearance of bilaterians or cnidarians.
Postulated relationship of Ediacaran frond-like animals Charniodiscus oppositus, Thaumaptilon walcotti and Yunnanozoon lividum and crown group cnidarians.
Thaumaptilon is considered to be a stem group cnidarian, Yunnanozoon a stem group bilaterian and Charniodiscus a stem group eumetazoan.
www.acs.appstate.edu /dept/biology/faculty/dewelra.htm   (512 words)

 Fred Heeren, Evolution and Cognition Journal
The discoverer of Cathaymyrus thought Yunnanozoon looked more like a hemichordate (acorn worm) than a chordate (SHU/ZHANG/ CHENG 1996); and the discoverer of Yunnanozoon opined that his challenger had mistaken Cathaymyrus’s squashed dorsal fin for a notochord (CHEN/ HUANG/LI, 1999b).
He remarked on the great number of specimens with conspicuous gill slits (for straining food out of the water) and other diagnostic characters: “The muscle segments are unarguable, and the notochord’s good too” (HOLLAND 1999).
Biologists had assumed that chordates did not develop the ability to accumulate minerals in their bodies to form teeth or bones until about 500 million years ago.
www.fredheeren.com /evocognition2.htm   (2430 words)

 Chordate - Medicow   (Site not responding. Last check: 2007-09-10)
A new chordate Yunnanozoon lividum, a cephalochordate, was found 1995 in Chengjiang, China.
Haikouella, a chordate similar to Yunnanozoon, but with additional traits, such as a heart and a relatively larger brain (Chen et al.
Anatomic findings such as the brain and possible lateral eyes in its close relative Haikouella pose a question as to whether Yunnanozoon may also be an early craniate.
www.medicow.com /topics/Chordate   (2865 words)

 The Cambrian Explosion and the Fossill Record
In a paper as similarly stunning as the Chen and Zhou article, the affinity of Yunnanozoon, previously incertae sedis, seems finally convincingly interpreted as a chordate.
Chen and Li provide not only many excellent color photographs, but also a good explanation of their comparison of Yunnanozoon with the Recent chordate Branchiostoma.
However, like the Chen and Zhou paper, this one fails to consistently provide a sense of scale in the figures, but also adds the annoyance of often referring to specimen numbers rather than figure numbers in text discussions.
www.nhm.ac.uk /hosted_sites/pe/1999_1/books/cheng.htm   (1250 words)

 3 Finds Clarify Life's Murky Origins - New York Times
Later evolution, they liked to think, could imply advanced and special status to the branch of life leading to humans.
In a report in the journal Nature, Dr. Lars Ramskold, a paleontologist at the University of Uppsala in Sweden, and colleagues said they had identified 525-million-year-old fossils of a strange, fishlike creature, which they have named Yunnanozoon lividum.
The researchers said Yunnanozoon appeared to belong to the division of chordates known as cephalochordates, which are closely related to backboned animals, including humans, but not of them.
query.nytimes.com /gst/fullpage.html?res=9C07E7DD1639F932A05753C1A963958260&sec=health&pagewanted=2   (698 words)

New York Time published news commentary article appreciating the fossil findings of Chengjiang fauna as the extraordinary discovery of the 20 Century in 1991.
In 1995, the newspaper again published a commentary article "From Yunnanozoon to You", appreciating the reinterpretation of Yunnanozoon as a chordate.
Science News published two cover articles, appreciating the findings of early giant predator in 1994 and the reinterpretation of Yunnanozoon as chordate in 1995.
www.nsfc.gov.cn /e_nsfc/desktop/dtxw.aspx@infoid=5421.htm   (1041 words)

 Haikouella lanceolata Fossils
Description: This exceptional specimen is a multiple (at least seven specimens) example of Haikouella lanceolata, thought by its describers to be the earliest craniate-like chordate.
This fish-like animal has many similarities to the contemporaneous Yunnanozoon lividum, but differs in several aspects: it has a discernible heart, dorsal and ventral aorta, gill filaments, and a neural chord.
For all these reasons, it was identified by Chen, Huang, and Li in the seminal Nature paper (Nature 402, 518-522, 02 December 1999) as a chordate.
www.fossilmall.com /EDCOPE_Enterprises/Chengjiang/chengjiangfossil5/chengjiangfossils-5.htm   (259 words)

I'm sure their neighbours thought they would never amount to anything.
Yunnanozoon is a weirdo that could either represent an extinct group of early chordates, an early hemichordate or something teetering on the chordate/hemichordate borderline.
A form known as Cheungkongella was also thought to be a seasquirt but has since turned out to be a syonym of Phlogites, a weird lophophorate (ie.
www.cryptozoology.com /forum/topic_view_thread.php?tid=12&pid=240927   (473 words)

 Unearthing The First Vertebrates | Science and Technology | BBC World Service
At least some of these are believed to be chordates, members of the large group that has few primitive members today but also includes all vertebrates - fish, reptiles, mammals and even ourselves.
Hundreds of specimens of a creature called Yunnanozoon have been discovered.
While some believe they are more primitive, perhaps even just worms, my Chinese hosts are sure that they are chordates, creatures like animated anchovy fillets with a rudimentary nervous system along a spinal cord plus gill slits and the typical zigzag muscle blocks of vertebrates.
www.bbc.co.uk /worldservice/sci_tech/highlights/001214_cambrian.shtml   (881 words)

 Fossil Fortune Cookie   (Site not responding. Last check: 2007-09-10)
But the matter is more debatable for the strange fossil Yunnanozoon, also from Chengjiang.
Some researchers think that Yunnanozoon represents a whole group of extinct chordates.
Dr Shu and colleagues disagree, placing it among distant relatives of chordates called hemichordates.
www.geology.ucdavis.edu /~cowen/HistoryofLife/Cathaymyrus.html   (666 words)

 The Cambrian Explosion
The sudden burst of life was new and strange.
We see our first ancestor, the Pikaia also called Yunnanozoon, which was an early chordate, the group containing vertebrates.
As mentioned before, worms were abundant such as the Canadia, a polychaete worm, and
library.thinkquest.org /3017/cambrian.htm   (586 words)

 [No title]
The course involved a wide range of compulsory geological modules but allowed me to focus on palaeobiology and evolution via the optional modules.
My 3rd year dissertation investigated the affinities of Yunnanozoon and the evolution of vertebrates.
The 4th year gave freedom for independent research and my 4th year project involved a detailed study of the ostracod colonisation of Rutland water (a 27 year old man made lake near Leicester).
home.btconnect.com /vw13   (271 words)

 TIME.com: WHEN LIFE EXPLODED -- Dec. 4, 1995 -- Page 2
Just last month, in an article published by the journal Nature, an international team of scientists reported finding the exquisitely preserved remains of a 1-in.- to 2-in.-long animal that flourished in the Cambrian oceans 525 million years ago.
From its flexible but sturdy spinal rod, the scientists deduced that this animal--dubbed Yunnanozoon lividum, after the Chinese province in which it was found--was a primitive chordate, the oldest ancestor yet discovered of the vertebrate branch of the animal kingdom, which includes Homo sapiens.
Even more tantalizing, paleontologists are gleaning insights into the enigmatic years that immediately preceded the Cambrian explosion.
www.time.com /time/magazine/article/0,9171,983789-2,00.html   (672 words)

 J32 The importance of the Burgess Shale
Paleontologists have since found extraordinarily well preserved fossils of Early Cambrian animals at two additional sites: outer-continental shelf facies (about 518 My) at Passet Sirius, northern Greenland,
at Chengjiang, southwestern China, with many bizarre animals as Yunnanozoon (securely identified by D. Snu in 1966 from fossils of its juveniles and adults as the earliest known hemichordate),
Halkieriid (previously known only from abundant isolated scales in "small shelly fauna" of earliest Cambrian age and now seen from a complete specimen collected by Conway Morris in 1984
geowords.com /histbooknetscape/j32.htm   (1022 words)

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