375 Million Year Old Fossil Show Evolution Of Hind Legs Started As Enhanced Fish Fins

The discovery of new fossil samples of a 375 million year old fish show that the development of hind legs happened before vertebrates transitioned to land and not after. The fossils show that legs started off as enhanced fish fins.

The fossils were of the prehistoric fish, Tiktaalik roseae, which is known as a transitional species between fish and land animals. The discovery of a well-preserved pelvis and a partial pelvic fin of the fish suggest that the development of hind legs started in fishes and not in land dwelling animals.

The pelvis had features comaprable to early tetrapods. It had a ball and socket hip joint and a highly mobile femur. Crests on the hip for muscle attachment indicated strength and advanced fin function. And although no femur bone was found, pelvic fin material, including long fin rays, indicated the hind fin was at least as long and as complex as its forefin.

The Tiktaalik roseae has a broad flat head and sharp teeth. Looking like a cross between a fish and a crocodile, the lobe finned fish can grow up to nine feet in length. Aside from having gills, scales, and fins, the prehistoric fish also had features found in land animals such as a mobile neck, robust ribcage and primitive lungs.

Tiktaalik roseae also had shoulders, elbows and partial wrists in its large forefins to provide support when it hunted in shallow freshwater environments. The researchers believe that aside from using the fins to swim like a paddle, the fish can also use it to walk with them as well.

Prehistoric Shark Exhibited Migratory Spawning Behavior Similar to Salmon

Artist impression of Prehistoric Bandringa Shark
Credit: John Megahan, University of Michigan

Paleontologist have discovered evidence of the migratory habit of the prehistoric shark, Bandringa. Fossil evidence show that the prehistoric shark bred in the ocean and migrated to freshwater.

Modern day sharks are not known to do follow this habit and the discovery is the only known example of a freshwater to saltwater shark migration.

Their spawning behavior left evidence of the earliest known shark nursery in the preserved fossilized egg cases and juvenile sharks found in the sediments.

The Bandringa is one of the closest relative of modern day shark and is similar to the sawfish and paddlefish. Just like the two, Bandringa has a spoon-billed snout up to half its body length. Young Bandringa sharks are about 4 to 6 inches long but can grow up to 10 feet upon maturity.

The 310 million year old shark was first found in fossil deposits in Mazon Creek, Illinois. It is a bottom-feeding predator and are known for for their extremely long spoonbill snouts. Because adult fossils have been only found at freshwater locations, it is believed that the shark lived exclusively in freshwater swamps and rivers.

Fossilized Pollen Suggests Flowering Plants Evolved 250 Million Years Ago

Fossilized pollen from the Triassic Period 250 million years ago
Credit: University of Zürich

Using Confocal Laser Scanning Microscopy, scientists have imaged fossilized pollen grains from Northern Switzerland that dates the evolution of flowering plants to the early Triassic Period around 252 to 247 million years ago. The three dimensional high resolution images of six different types of pollen also suggest that the plants were pollinated by insects.

The Triassic period extends to about 250 to 200 million years ago and is the first period of the Mesozoic Era. This period lies between the Permian and Jurassic periods.

During the Triassic period, the Earth's climate was generally hot and dry and that there are no evidence of glaciers at or near the north and south pole. During this time, the polar regions were moist and temperate. It would have a climate that is suitable for forests and vertebrarates.

The Earth's continents would not have existed then. The land mass of the planet then was one gigantic continent called Pangea. The climate on Pangea was seasonal having hot summers and cold winters.

Plant life during this time was believed to include lycophytes, cycads, ginkgophyta (represented in modern times by Ginkgo biloba) and glossopterids. Seed plants such as spermatophytes are abundant in the north while Glossopteris (a seed fern) was the dominant tree in the southern hemisphere.

The discovery of the pollen would place the appearance of flowering plants during this period, 100 million years earlier than previously believed.

Darwin's Evolution Through Natural Selection Consistent With Cambrian Explosion

This image shows marine life during the Cambrian explosion (~520 million years ago). A giant Anomalocaris investigates a trilobite, while Opabinia looks on from the right and the "walking cactus" Diania crawls underneath. All of these creatures are related to living arthropods.
Credit: Katrina Kenny & Nobumichi Tamura

Scientists report that Charles Darwin's evolution through natural selection theory is consistent with the sudden diversity of life during the Cambrian explosion. Their study shows that a sustained accelerated rate of evolution over millions of years would have resulted in an increased rate of over five times; 100 million years of evolutionary change would have only took about 20 million years.

580 million years ago, living organisms were mostly simple cells that occasionally organized into colonies. The following 70 to 80 million years suddenly showed a diverse amount of life that included animals, phytoplankton, and calcimicrobes.

This period of the Earth's history is called the Cambrian explosion. During this period, the evolutionary rate of living organisms accelerated and the diversity of living organisms began to resemble that of organisms today.

Fossil records have shown the results and aftermath of the Cambrian explosion but the reason for it to happen and why it has not repeated again is still a mystery.

Climate During the Pliocene Period May Help Improve Climate Change Predictions

Researchers are looking back to climate conditions during the Pliocene Period, 4 to 5 million years ago, to develop a more improved model in predicting future climate change.

The climate during the Pliocene period was similar to the climate of modern times. It was cooler, drier and also experienced seasons just as today. The temperature then was around 2-3°C higher than today and sea level was 25 meters higher. Ocean temperature

The warm period during the mid-Pliocene epoch can be considered as a model of future climate today. The heat from the sun, geography and CO2 levels were similar to what it is now.

By studying the climate during the Pliocene period, researchers are hoping to find previously unknown mechanisms that may give insight on how climate reacts to certain conditions.

Discovery of Unknown Worm Fossil at Burgess Shale Hailed As Major Scientific Find

Undescribed species of a modern enteropneust (ptychoderid) worm. The proboscis is to the left. The total length of a relaxed and uncoiled animal is approximately 88 mm.
Credit: Photo: C.B. Cameron, Université de Montréal.

The discovery of fossils of previously unknown soft bodied worms at the Burgess Shale is being hailed as a significant find and offer a wider perspective on the diversity of life during the Cambrian period.

Shale is a clastic (composed of fragments) sedimentary rock that is fine grained and made up of mud. The mud in shale is composed of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite.

In Yoho National Park located in the Canadian Rockies of British Columbia is the fossil field known as the Burgess Shale. It contains some of the most important and significant fossil deposits dating back to the Middle Cambrian period, 505 million years ago. The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park.

The rapid appearance of most major animal phyla in the fossil record accompanied by major diversification of organisms including animals, phytoplankton, and calcimicrobes made the Cambrian period an important point in the history of life on Earth. The period between 530 million and 550 million years ago is known as the Cambrian explosion due to the sudden diversity of life discovered living then.

Burgess Shale was discovered by Charles Walcott in 1909. And during the time of discovery up to the death of Walcott in 1927, some 65,000 specimens have been discovered already. Even after this, the fossil field has still yielded significant amounts of fossils that gave a glimpse of the diversity of life around 500 million years ago.

Fossil of Giant Camel That Lived During the Pliocene Period Found In Canada's High Arctic

Scientists found fossil fragments of what could be an extinct giant camel that lived during the Pliocene period.

The Pliocene epoch is the period of the Earth 5.3 to 5.6 million years ago. This succeeds the Miocene era where open vegetation systems (such as deserts, tundra, and grasslands)start expanding while closed vegetation systems like forests diminish.

The Pliocene era was much cooler than the Miocene era which further contributed to the expansion of open vegetation systems. This change in vegetation was a major factor in the development and spread of long legged grazers that thrive in these places.

The land-bridge between North America and South America also appeared during this period. This allowed the migration of plants and animals into new habitats. The Pliocene era also led to the accumulation of ice at the Earth's poles. This led to the extinction of most species there as well was the advance of glaciers and ice ages of the Late Pliocene and the following Pleistocene.

The Pliocene was followed by the Miocene era which was characterized by the presence of distinctive large land mammals such as (Mammoths, and Mastodons) and birds. The total collection of organisms during the Miocene resembles the ones found today.

It was during the Pliocene where the extinct giant camel found in Canada's High Arctic was found.

This is an illustration of the High Arctic camel on Ellesmere Island during the Pliocene warm period, about three-and-a-half million years ago. The camels lived in a boreal-type forest. The habitat includes larch trees and the depiction is based on records of plant fossils found at nearby fossil deposits.
Credit: Julius T. Csotonyi