Hallucigenia:  Worm-like creature with legs and spikes finds its place in the evolutionary tree of life
via: University of Cambridge
One of the most bizarre-looking fossils ever found - a worm-like creature with legs, spikes and a head difficult to distinguish from its tail – has found its place in the evolutionary Tree of Life, definitively linking it with a group of modern animals for the first time.
The animal, known as Hallucigenia due to its otherworldly appearance, had been considered an ‘evolutionary misfit’ as it was not clear how it related to modern animal groups. Researchers from the University of Cambridge have discovered an important link with modern velvet worms, also known as onychophorans, a relatively small group of worm-like animals that live in tropical forests. The results are published in the advance online edition of the journal Nature.
The affinity of Hallucigenia and other contemporary ‘legged worms’, collectively known as lobopodians, has been very controversial, as a lack of clear characteristics linking them to each other or to modern animals has made it difficult to determine their evolutionary home…
(read more: PhysOrg)
illustration by Elyssa Rider

Hallucigenia:  Worm-like creature with legs and spikes finds its place in the evolutionary tree of life

via: University of Cambridge

One of the most bizarre-looking fossils ever found - a worm-like creature with legs, spikes and a head difficult to distinguish from its tail – has found its place in the evolutionary Tree of Life, definitively linking it with a group of modern animals for the first time.

The animal, known as Hallucigenia due to its otherworldly appearance, had been considered an ‘evolutionary misfit’ as it was not clear how it related to modern animal groups. Researchers from the University of Cambridge have discovered an important link with modern velvet worms, also known as onychophorans, a relatively small group of worm-like animals that live in tropical forests. The results are published in the advance online edition of the journal Nature.

The affinity of Hallucigenia and other contemporary ‘legged worms’, collectively known as lobopodians, has been very controversial, as a lack of clear characteristics linking them to each other or to modern animals has made it difficult to determine their evolutionary home…

(read more: PhysOrg)

illustration by Elyssa Rider

dendroica
palaeopedia:

The Hallucigenia (1977)
Phylum : LobopodiaOrder : ScleronychophoraFamily : HallucigeniidaeGenus : HallucigeniaSpecies : H. sparsa, H. fortis, H. hongmeia
Late Cambrian (505 Ma)
3,5 cm long (size)
Canada (map)
Hallucigenia is a 0.5—3.5 cm long tubular organism with seven or eight pairs of slender legs, each terminating with a pair of claws. Above each leg is a rigid conical spine. The ‘head’ and ‘tail’ end of the organism are difficult to identify; one end extends some distance beyond the legs and often droops down as if to reach the floor. Although some specimens display traces of a gut, the internal anatomy has not been formally described.
Hallucigenia’s spines are made up of one to four nested elements. Their surface is covered in an ornament of minute triangular ‘scales’.
Hallucigenia was originally described by Walcott as a species of the polychaete worm Canadia. In his 1977 redescription of the organism, Simon Conway Morris recognized the animal as something quite distinct, establishing the new genus. No specimen was available that showed both rows of legs, and as such Conway Morris reconstructed the animal walking on its spines, with its single row of legs interpreted as tentacles on the animal’s back. A dark stain at one end of the animal was interpreted as a featureless head. Only the forward tentacles could easily reach to the ‘head’, meaning that a mouth on the head would have to be fed by passing food along the line of tentacles. Conway Morris suggested that a hollow tube within each of the tentacles might be a mouth. This raised questions such as how it would walk on the stiff legs, but it was accepted as the best available interpretation. A picture of the animal as reconstructed by Morris can be found here.
An alternative interpretation considered Hallucigenia to be an appendage of a larger, unknown animal. There had been precedent for this, as the species Anomalocaris had been originally identified as three separate creatures before being identified as a single huge (for its time) 0.91 m creature. Given the uncertainty of its taxonomy, Hallucigenia was tentatively placed within the phylum Lobopodia, a catch-all clade containing numerous odd “worms with legs.”
In 1991, Lars Ramskold and Hou Xianguang, working with additional specimens of a “hallucigenid,” Microdictyon, from the lower Cambrian Maotianshan shales of China, reinterpreted Hallucigenia as an Onychophoran (velvet worm). They inverted it, interpreting the tentacles, which they believe to be paired, as walking structures and the spines as protective. Further preparation of fossil specimens showed that the ‘second legs’ were buried at an angle to the plane along which the rock had split, and could be revealed by removing the overlying sediment. Ramskold and Hou also believe that the blob-like ‘head’ is actually a stain that appears in many specimens, not a preserved portion of the anatomy.

palaeopedia:

The Hallucigenia (1977)

Phylum : Lobopodia
Order : Scleronychophora
Family : Hallucigeniidae
Genus : Hallucigenia
Species : H. sparsa, H. fortis, H. hongmeia

  • Late Cambrian (505 Ma)
  • 3,5 cm long (size)
  • Canada (map)

Hallucigenia is a 0.5—3.5 cm long tubular organism with seven or eight pairs of slender legs, each terminating with a pair of claws. Above each leg is a rigid conical spine. The ‘head’ and ‘tail’ end of the organism are difficult to identify; one end extends some distance beyond the legs and often droops down as if to reach the floor. Although some specimens display traces of a gut, the internal anatomy has not been formally described.

Hallucigenia’s spines are made up of one to four nested elements. Their surface is covered in an ornament of minute triangular ‘scales’.

Hallucigenia was originally described by Walcott as a species of the polychaete worm Canadia. In his 1977 redescription of the organism, Simon Conway Morris recognized the animal as something quite distinct, establishing the new genus. No specimen was available that showed both rows of legs, and as such Conway Morris reconstructed the animal walking on its spines, with its single row of legs interpreted as tentacles on the animal’s back. A dark stain at one end of the animal was interpreted as a featureless head. Only the forward tentacles could easily reach to the ‘head’, meaning that a mouth on the head would have to be fed by passing food along the line of tentacles. Conway Morris suggested that a hollow tube within each of the tentacles might be a mouth. This raised questions such as how it would walk on the stiff legs, but it was accepted as the best available interpretation. A picture of the animal as reconstructed by Morris can be found here.

An alternative interpretation considered Hallucigenia to be an appendage of a larger, unknown animal. There had been precedent for this, as the species Anomalocaris had been originally identified as three separate creatures before being identified as a single huge (for its time) 0.91 m creature. Given the uncertainty of its taxonomy, Hallucigenia was tentatively placed within the phylum Lobopodia, a catch-all clade containing numerous odd “worms with legs.”

In 1991, Lars Ramskold and Hou Xianguang, working with additional specimens of a “hallucigenid,” Microdictyon, from the lower Cambrian Maotianshan shales of China, reinterpreted Hallucigenia as an Onychophoran (velvet worm). They inverted it, interpreting the tentacles, which they believe to be paired, as walking structures and the spines as protective. Further preparation of fossil specimens showed that the ‘second legs’ were buried at an angle to the plane along which the rock had split, and could be revealed by removing the overlying sediment. Ramskold and Hou also believe that the blob-like ‘head’ is actually a stain that appears in many specimens, not a preserved portion of the anatomy.

palaeopedia
palaeopedia:

The mount Wapta’s one, Waptia (1912)
Phylum : ArthropodaClass : CrustaceomorphaOrder : WaptiidaFamily : WaptiidaeGenus : WaptiaSpecies : W. fieldensis
Middle Cambrian (505 Ma)
8 cm long (size)
Canada (map)
Waptia fieldensis had a maximum body length of 8 centimetres. The exoskeleton was very thin and easily distorted from fossilisation. It possessed a large bivalved carapace that was narrow at the front with wide posterior margins that covered the cephalon and most of the thorax. The cephalon had five short somites (body segments) with three to five pairs of small and poorly preserved feeding appendages…
(read more)

palaeopedia:

The mount Wapta’s one, Waptia (1912)

Phylum : Arthropoda
Class : Crustaceomorpha
Order : Waptiida
Family : Waptiidae
Genus : Waptia
Species : W. fieldensis

  • Middle Cambrian (505 Ma)
  • 8 cm long (size)
  • Canada (map)

Waptia fieldensis had a maximum body length of 8 centimetres. The exoskeleton was very thin and easily distorted from fossilisation. It possessed a large bivalved carapace that was narrow at the front with wide posterior margins that covered the cephalon and most of the thorax. The cephalon had five short somites (body segments) with three to five pairs of small and poorly preserved feeding appendages…

(read more)

Primeval Predators

These scientifically accurate toys are based on the half-billion-year-old fossils of the Burgess Shale from the Canadian Rockies of British Columbia. The ancestors of all animal groups appeared in the greatest evolutionary explosion of all time – the Big Bang of evolution – 500 million years ago. The best view we have of these first animal communities on Earth exists in the Burgess Shale fossils first discovered on Mt. Stephen in 1886. In 1975, Dr. Desmond Collins led the first ROM expedition to the Burgess Shale. He returned for 18 seasons and discovered new Burgess Shale fossil sites and collected many thousands of unique and bizarre fossils…

(find out more: Royal Ontario Museum)

* thanks to CrankyDinosaur for letting us know about this.

Oxygen Brought Earliest Carnivores to Life
by Becky Oskin
Without oxygen, there would be no carnivores. Without carnivores, there would be no Cambrian explosion, the stunning evolutionary burst of diversity in species and body forms that began 540 million years ago.
Those are the findings of a new study that stitches together competing models for why meat-eating appeared simultaneously with the Cambrian explosion. Previously, one camp of scientists had proposed that rising oxygen levels gave animals the extra power to evolve complex body forms. Another school of thought said that competition among animals drove the sudden appearance of new species, such as the weird and wild life forms found in the Burgess Shale, a rock formation in Canada that has been an amazing source of fossils.
"There’s always been this tension," said lead author Erik Sperling, a postdoc at Harvard University. “Each side is looking at their own data, which is often common in science.”…
(read more: Live Science)
illustration - Orthrozanclus reburrus, by Marianne Collins (C) AAAS/Science-2007

Oxygen Brought Earliest Carnivores to Life

by Becky Oskin

Without oxygen, there would be no carnivores. Without carnivores, there would be no Cambrian explosion, the stunning evolutionary burst of diversity in species and body forms that began 540 million years ago.

Those are the findings of a new study that stitches together competing models for why meat-eating appeared simultaneously with the Cambrian explosion. Previously, one camp of scientists had proposed that rising oxygen levels gave animals the extra power to evolve complex body forms. Another school of thought said that competition among animals drove the sudden appearance of new species, such as the weird and wild life forms found in the Burgess Shale, a rock formation in Canada that has been an amazing source of fossils.

"There’s always been this tension," said lead author Erik Sperling, a postdoc at Harvard University. “Each side is looking at their own data, which is often common in science.”…

(read more: Live Science)

illustration - Orthrozanclus reburrus, by Marianne Collins (C) AAAS/Science-2007

Opabinia

… is an extinct stem-arthropod genus found in Cambrian fossil deposits. The only known species, O. regalis, is known from the Middle Cambrian Burgess Shale Lagerstätte of British Columbia, Canada. Fewer than twenty good specimens have been described; 3 specimens of Opabinia are known from the Greater Phyllopod bed, where they comprise less than 0.1% of the community.

Opabinia was a soft-bodied animal of modest size, and its segmented body had lobes along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food…

(read more: Wikipedia)                    (illustrations by Nobu Tamura)

lostbeasts
alphynix:

Wiwaxia was one of the bizarre animals found in the 505-million-year-old Burgess Shale Formation of British Columbia, Canada.
Squashed flat in the rocks, these 5cm (2”) spiny creatures were difficult to analyze and reconstruct, and what exactly they were is still being debated. For many years they were tentatively considered to be distant relatives of polychaete or annelid worms, but more recent studies and better microscopic imaging techniques have found a primitive radula-like structure in their mouths — suggesting that they might actually be closer related to molluscs.
The armour coat of scale-like sclerites and the long asymmetrical rows of spines were probably a defense against predators. I’ve given it a splash of some sea-slug warning colors here just for fun.

alphynix:

Wiwaxia was one of the bizarre animals found in the 505-million-year-old Burgess Shale Formation of British Columbia, Canada.

Squashed flat in the rocks, these 5cm (2”) spiny creatures were difficult to analyze and reconstruct, and what exactly they were is still being debated. For many years they were tentatively considered to be distant relatives of polychaete or annelid worms, but more recent studies and better microscopic imaging techniques have found a primitive radula-like structure in their mouths — suggesting that they might actually be closer related to molluscs.

The armour coat of scale-like sclerites and the long asymmetrical rows of spines were probably a defense against predators. I’ve given it a splash of some sea-slug warning colors here just for fun.

Opabinia is an extinct stem-arthropod genus found in Cambrian fossil deposits. The only known species, O. regalis, is known from the Middle Cambrian Burgess Shale Lagerstätte of British Columbia, Canada. Fewer than twenty good specimens have been described. Opabinia was a soft-bodied animal of modest size, and its segmented body had lobes along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food…
(read more: Wikipedia)                                (image: Nobu Tamura)

Opabinia is an extinct stem-arthropod genus found in Cambrian fossil deposits. The only known species, O. regalis, is known from the Middle Cambrian Burgess Shale Lagerstätte of British Columbia, Canada. Fewer than twenty good specimens have been described. Opabinia was a soft-bodied animal of modest size, and its segmented body had lobes along the sides and a fan-shaped tail. The head shows unusual features: five eyes, a mouth under the head and facing backwards, and a proboscis that probably passed food to the mouth. Opabinia probably lived on the seafloor, using the proboscis to seek out small, soft food…

(read more: Wikipedia)                                (image: Nobu Tamura)

dailyfossil

dailyfossil:  Perspicaris

Reconstruction by Marianne Collins

When: Cambrian (~505 million years ago)

Where: Specimens first known from the Burgess Shale of Canada, now possibly found in other sites in North America of similar ages. 

What: Perspicaris is another enigmatic stem arthropod from the Burgess Shale fossil lagerstatten deposit. It is a bivalve arthropod, like our last Burgess Shale fossil Tuzoia, but has more bits than just its eyes sticking out, so more conclusions as to its life style can be drawn.  Sticking out from the front of its carapace are eyes and relatively thick antennae and emerging posteriorly is a powerful tail.  Perspicaris swam though the water column under its own power, but swam to the bottom of the paleo-ocean to feed.  Sediment preserved in the gut of a few specimens shows this animal was a deposit feeder; consuming loose mud on the ocean floor and processing all minute food particles from these sediment grains. 

The evolutionary relationships of Perspicaris are not well known, like Tuzoia it is proposed to either be related to a subgroup of crustaceans or to be a stem taxon to all living arthropods. As you probably have concluded, the relationships between all of these taxa is an area of paleontology that really needs more people working on it! 

dailyfossil

dailyfossil:  Fasciculus

When: Cambrian (~505 million years ago)

Where: Canada

What: Fasciculus is yet another fantastic fossil from the Burgess Shale fossil site in BC, Canada. It is extremely rare, with only one known specimen. This single specimen was found in 1917, but not fully described in detail until 1996. It is about 4.5 inches (11.4 cm) wide, and is perserved in intricate detail.

Unlike most fossils from the Burgess Shale, Fasciculus is confidently linked to a living group. It is placed as a stem Ctenophora,which are the comb-jellies. Comb-jellies are not closely related to ‘normal’ jellyfish, which fall into the cnidaria along with the hydras. Ctenophoras are cup-like animals that swim though the water, with multiple sets of cilia arranged in longitudinal series, so that they resemble combs, giving them their common name of comb-jelly. In Fasciculus you can see these rows wonderfully preserved. The discovery of a stem member of this lineage once again shows that most, if not all, modern phyla were well separated even as long ago as the Cambrian.  

For more read up on this very rare fossil and its contemporaries at: http://burgess-shale.rom.on.ca/en/index.php

Reconstruction by Marianne Collins

scientificillustration

dailyfossil:   Opabinia

When: Mid-Cambrian (515-500 million years ago)

Where: British Columbia, Canada. 

What: Opabinia is one of the rarest forms from the Burgess Shale fossil lagerstatten. We have explored the Burgess Shale fauna before with Anomalocaris and Hallucigenia. Opabinia, unlike these other species, has not had a confusing history with various interpretations of its anatomy. This does not mean that 1.5-3 inch (4-7cm) long invertebrate is much like any modern form though! Far from it, Opabinia is unlike anything alive today. Much of its body resembled Anomalocaris, which it is possibly related to, but its head is where the most bizarre features were. It had 5 eyes and a proboscis up to 1/3rd of its length, ending in a form of gripping claw. This proboscis was flexible enough to curve around to its mouth, which was hidden on the underside of its head and directed posteriorly.  It is thought Opabinia swam though the ancient seas by flexing its body, picking up soft bodied prey animals with this ‘trunk’. No traces of legs have been found in any of the ~20 or so fossil specimens. 

Like most Burgess Shale taxa, the relationships of Opabinia are uncertain. It is somewhat hesitatingly placed as a stem arthropod in a lot of classifications, but this relationship is based in turn on an uncertain link with Anomalocaris. It is possible that Opabinia is far removed from all modern phyla. One of the biggest supports for this later view is its 5 eyes, a configuration never again seen in the history of life. 

I might have gone a bit overboard with the images today, but this is one of my most favorite fossil forms! It is just so odd and different from anything else.