Carboniferous animal trackway discovery, Grand Canyon, USA

Manakacha Trackway, photo by Stephen Rowland

From the National Park Service in the USA:

Cliff collapse reveals 313-million-year-old fossil footprints in Grand Canyon National Park

August 21, 2020

Paleontological research has confirmed a series of recently discovered fossils tracks are the oldest recorded tracks of their kind to date within Grand Canyon National Park. In 2016, Norwegian geology professor, Allan Krill, was hiking with his students when he made a surprising discovery. Lying next to the trail, in plain view of the many hikers, was a boulder containing conspicuous fossil footprints. Krill was intrigued, and he sent a photo to his colleague, Stephen Rowland, a paleontologist at the University of Nevada Las Vegas.

The trailside tracks have turned out to be even more significant than Krill first imagined. “These are by far the oldest vertebrate tracks in Grand Canyon, which is known for its abundant fossil tracks” says Rowland. “More significantly,” he added, “they are among the oldest tracks on Earth of shelled-egg-laying animals, such as reptiles, and the earliest evidence of vertebrate animals walking in sand dunes.”

The track-bearing boulder fell from a nearby cliff-exposure of the Manakacha Formation. The presence of a detailed geologic map of the strata along the Bright Angel Trail, together with previous studies of the age of the Manakacha Formation, allowed the researchers to pin down the age of the tracks quite precisely to 313 +/- 0. 5 million years.

The newly discovered tracks record the passage of two separate animals on the slope of a sand dune. Of interest to the research team is the distinct arrangement of footprints. The researchers’ reconstruction of this animal’s footfall sequence reveals a distinctive gait called a lateral-sequence walk, in which the legs on one side of the animal move in succession, the rear leg followed by the foreleg, alternating with the movement of the two legs on the opposite side. “Living species of tetrapods―dogs and cats, for example―routinely use a lateral-sequence gait when they walk slowly,” says Rowland. “The Bright Angel Trail tracks document the use of this gait very early in the history of vertebrate animals. We previously had no information about that.” Also revealed by the trackways is the earliest-known utilization of sand dunes by vertebrate animals.

Grand Canyon, USA wildlife, and mercury pollution

This 2016 video from the USA is called Grand Canyon Wildlife.

From the Cary Institute of Ecosystem Studies in the USA:

Food webs determine the fate of mercury pollution in the Colorado River, Grand Canyon

Floods can shift animal populations, altering mercury passed to fish and other wildlife

May 15, 2020

In the Grand Canyon reach of the Colorado River, two species play an outsized role in the fate of mercury in the aquatic ecosystem, and their numbers are altered by flood events. So reports new research, published in Science Advances, that is among the first to meld ecotoxicology and ecosystem ecology to trace how mercury flows through aquatic food webs and then spreads to land.

Mercury is an environmental contaminant that occurs in ecosystems globally. In its organic form, it is a potent neurotoxin that can harm people and wildlife. Mercury accumulation in animals and how it magnifies along food chains is well studied. Less well understood are the pathways mercury takes through food webs to reach top predators, such as fish and birds, and how those pathways might change after large ecosystem disturbances, such as floods.

Emma Rosi is an aquatic ecologist at Cary Institute of Ecosystem Studies and co-lead author on the paper. She explains, “By combining data on mercury concentrations in aquatic life with well-studied food webs, we were able to reveal how mercury moves through an ecosystem. We found that flooding and an invasive species both influenced the flow of this contaminant of global concern.”

The traits of organisms living in an ecosystem — their physiology, what they eat, and what eats them — determine contaminant movement and exposure. These factors have rarely been included in models of contaminant flux and fate. “Pairing contaminant concentrations and highly detailed food webs has the potential to improve the management of contaminants in ecosystems,” Rosi notes.

To study these pathways, the research team developed mercury-based food webs for six sites spanning 225 miles of the Colorado River, extending downstream from the Glen Canyon Dam in Grand Canyon National Park. Food web sampling took place seasonally over two years. At each site, they measured algae, invertebrates, and fish to determine who was eating what — and what that meant for mercury exposure at each level of the food web.

Insects (blackflies and midges) and invasive New Zealand mudsnails were the dominant invertebrates in the river. These animals play a vital role in moving energy and contaminants from the bottom of the food web to fish predators at the top. Fish included native Bluehead Sucker, Flannelmouth Sucker, Speckled Dace, and Humpback Chub, as well as non-native species such as Common Carp, Fathead Minnow, and Rainbow Trout.

The stomach contents of invertebrates and fish were assessed to identify what they ate and in what amounts. Algae, detritus, and animals were analyzed for mercury concentrations and, combined with the diet data, the team estimated the amount of mercury that animals were consuming throughout the year.

Food web complexity varied across the study sites. Just below the Glen Canyon Dam, food webs were simple with few species and food web connections. Further downstream, food webs had higher species diversity and more connections. Across the study sites, regardless of food web complexity, relatively few species were key players in the movement of mercury.

Algae and tiny particles of detritus were the source of 80% of mercury flowing to invertebrates. In sites closest to the dam, invasive mudsnails dominated the food webs. Trout were the only fish in this part of the river, and they are unable to digest mudsnails. Mercury accumulated by the snails did not move up the food chain. Because the snails are fully aquatic, mercury cycled back into the river’s detrital food web when they died.

Blackfly larvae were the source of 56-80% of the mercury flowing to fish. Blackflies are preferred prey for fish, such as Rainbow Trout, and blackflies had higher mercury contaminations compared to other invertebrates. Blackflies that escape predation and emerge from the river as flying adults move mercury from the river to land. This can expose terrestrial predators, such as birds and bats, to mercury that started out in the river.

The amount of mercury that blackflies moved to land was dependent on the number of hungry fish in any part of the river. At some sites, fish ate nearly 100% of the blackfly larvae, leaving few left to emerge. At other sites, there were a lot more blackflies than the fish could eat. When these blackflies emerged as adults, the mercury inside them hitched a ride to terrestrial food webs along the river.

One year into sampling, the study sites were flooded as part of a planned dam release. The team was able to explore the effects of the flood on mercury movement in the food webs. At sites near the dam, the flood washed away large numbers of New Zealand mudsnails and led to a boom in blackfly populations. With the rise in blackflies, more mercury flowed to trout. Because trout gobbled up nearly all the blackflies in their larval form, very little of the mercury accumulated in these abundant insects was transported to land by the flying adults.

Rosi explains, “Changes to the animal populations in an ecosystem will impact how mercury moves through a food web. This was especially apparent at sites where flooding changed the proportion of blackflies relative to fish. Flooding dramatically altered mercury pathways in the simple tailwater food web near the dam, but not in the more complex food webs downstream.”

“Invasive species and dams are common in rivers globally, and both factors were at play in the Grand Canyon reach of the Colorado River,” Rosi says. “We found that flooding changed the species present at our study sites, and mercury flow changed with those shifts.”

“Understanding the factors that control the movement of mercury through food webs can help resource managers protect ecosystems that are susceptible to mercury pollution,” says David Walters, USGS scientist and co-lead author of the study.

Rosi concludes, “This study is exciting because it sheds light on the depth of understanding we can achieve when we merge ecological and ecotoxicological thinking. Species traits, animal populations, predator-prey interactions, and disturbance can all influence the movement of contaminants in the environment. Understanding the complex interplay of these factors can improve risk management of animal exposures in the environment.”

Grand Canyon woodpeckers defend food against squirrel

This 18 June 2019 video from the USA says about itself:

In the Grand Canyon, woodpeckers store their food in hollowed out holes in trees, but when a squirrel tries to steal the supply – they defend their stockpile.

Oldest reptile tracks in Grand Canyon, USA

UNLV geologist Stephen Rowland discovered that a set of 28 footprints left behind by a reptile-like creature 310 million years ago are the oldest ever to be found in Grand Canyon National Park. Credit: Stephen Rowland

From the University of Nevada, Las Vegas in the USA:

Tiny footprints, big discovery: Reptile tracks oldest ever found in Grand Canyon

Geologist investigating 310 million-year-old fossil trackway from ancient reptilian creature

November 8, 2018

A geology professor at the University of Nevada, Las Vegas, has discovered that a set of 28 footprints left behind by a reptile-like creature 310 million years ago, are the oldest ever to be found in Grand Canyon National Park.

The fossil trackway covers a fallen boulder that now rests along the Bright Angel Trail in the national park. Rowland presented his findings at the recent annual meeting of the Society of Vertebrate Paleontology.

“It’s the oldest trackway ever discovered in the Grand Canyon in an interval of rocks that nobody thought would have trackways in it, and they’re among the earliest reptile tracks on earth”, said Rowland.

Rowland said he’s not prepared to say that they’re the oldest tracks of their kind ever discovered, but it’s a possibility, as he’s still researching the discovery.

“In terms of reptile tracks, this is really old,” he said, adding that the tracks were created as the supercontinent Pangaea was beginning to form.

Rowland was first alerted to the tracks in spring 2016 by a colleague who was hiking the trail with a group of students. The boulder ended up along the trail after the collapse of a cliff.

A year later, Rowland studied the footprints up close.

“My first impression was that it looked very bizarre because of the sideways motion”, Rowland said. “It appeared that two animals were walking side-by-side. But you wouldn’t expect two lizard-like animals to be walking side-by-side. It didn’t make any sense.”

When he arrived home, he made detailed drawings, and began hypothesizing about the “peculiar, line-dancing gait” left behind by the creature.

“One reason I’ve proposed is that the animal was walking in a very strong wind, and the wind was blowing it sideways”, he said.

Another possibility is that the slope was too steep, and the animal sidestepped as it climbed the sand dune. Or, Rowland said, the animal was fighting with another creature, or engaged in a mating ritual.

“I don’t know if we’ll be able to rigorously choose between those possibilities”, he said.

He plans to publish his findings along with geologist Mario Caputo of San Diego State University in January. Rowland also hopes that the boulder is soon placed in the geology museum at the Grand Canyon National Park for both scientific and interpretive purposes.

Meanwhile, Rowland said that the footprints could belong to a reptile species that has never yet been discovered.

“It absolutely could be that whoever was the trackmaker, his or her bones have never been recorded,” Rowland said.

Save Grand Canyon in the USA from threats

This video from the USA says about itself:

LEAVE IT AS IT IS – The Colorado River in the Grand Canyon

6 April 2015

The Grand Canyon is one of the most iconic landscapes on the planet. But this natural masterpiece of the Colorado River faces a battery of threats. Unless the Department of the Interior acts to stop these threats, one of our nation’s greatest natural treasures will be scarred forever. Help protect it: here.

The grave new threat facing the Grand Canyon. A massive new development promises housing, hotels and boutiques. Opponents say it will deface a national monument: here.

Save the Grand Canyon wolf in the USA

This video from the USA says about itself:

Endangered Gray Wolf Could Be Roaming the Grand Canyon

3 November 2014

According to conservationists, a wayward gray wolf has been spotted several times this month around the North Rim of Grand Canyon National Park. The wolf, which is wearing an inactive radio collar, could be the first of its species to roam Arizona in 70 years; gray wolves were exterminated from the state in the 1940s. Federal authorities are investigating the sightings.

From the Center for Biological Diversity in the USA:


The wolf-haters‘ caucus is gunning for the Grand Canyon wolf, and all the other wolves who seek to reclaim their historic homeland. Help us stand up to wolf-hating politicians and keep wolves protected and free to roam. If you donate to the Predator Defense Fund now, your gift will be matched 2-to-1 by a generous supporter. Please stand with the Grand Canyon wolf today.

We’ve been top-rated by the American Institute of Philanthropy, and have more than two decades of success in saving endangered species and wildlands. You can trust us to make the most of your tax-deductible contribution.

Wolf travels 450 miles to Grand Canyon

This video from the USA is called Grand Canyon National Park.

From Wildlife Extra:

Gray wolf travels 450 miles to Grand Canyon

For the first time in 70 years a lone gray wolf has been sighted in Arizona. The female wolf originated from the northern Rocky Mountains and has travelled at least 450 miles to the North Rim of Grand Canyon National Park.

“This wolf’s epic journey through at least three western states fits with what scientific studies have shown, namely that wolves could once again roam widely and that the Grand Canyon is one of the best places left for them,” said Michael Robinson from the Center for Biological Diversity.

Gray wolves face an uncertain future. Almost 100 years ago, in 1915, the federal US government conducted began culling wolves in the western United States, and by the early 1920s most of the wolves had been exterminated and the last one was sighted Arizona in the 1940s. The Gray wolf was added to the country’s Endangered List and in the 1990s 66 wolves were brought to the Rocky Mountains.

As a result of this conservation work populations are increasing and the US Fish and Wildlife Service are now, due to the success, are proposing to remove the species from the list. But this has concerned some conservationists as they say without the protection the species could be persecuted again.

“It’s heartening this animal has been confirmed as a wolf. But I am very worried that if wolves are taken off the endangered species list she will be killed and wolf howls from the North Rim’s pine forest will never again echo in the Grand Canyon,” [said] Robinson.

Earlier this month, the Center released a first-of-its-kind analysis identifying 359,000 square miles of additional wolf habitat in the lower 48 states that could significantly boost wolf recovery which include Northeast, West Coast and southern Rocky Mountains, as well as the Grand Canyon.

“There’s so much more room for wolves in the West if only we extend them a bit more tolerance,” Robinson said. “The Grand Canyon wolf is a prime example of what wolves can do if only we let them.”

California condors still suffering from DDT

This is a California condor video from the USA.

Recent reports and studies of a struggling California condor population indicate the persistence of DDT contamination, underscoring long-standing concerns that the chemical pesticide and its related byproduct chemicals continue to threaten animal life and affect human health: here.

April 2011: Lead ammunition is a primary factor limiting the survival and recovery of the Californian condor, one of America’s most endangered birds, according to a new study: here.

June 2011: Recent episodes of lethal lead poisoning in California condors have biologists asking for more help from the public to conserve endangered condors in northern Arizona and southern Utah: here.

May 2011: A California condor chick has hatched in the wild at a new nest site near Vermilion Cliffs National Monument, northeast of the Grand Canyon: here.

Three California condors will be released to the wild in the Vermilion Cliffs National Monument in northern Arizona next month: here.

Scientific paper shows California condor still threatened by human activities: here.

California condors numbers pass the 400 mark for the first time for 100 years: here.

A comprehensive study led by environmental toxicologists at the University of California, Santa Cruz, shows that California condors are continually exposed to harmful levels of lead, the principal source of that lead is ammunition, and lead poisoning from ammunition is preventing the recovery of the condor population: here.

August 2012. A Peregrine Fund biologist has provided visual confirmation that a wild-hatched California condor chick is present in a nest cave deep in Grand Canyon National Park. That brings to three the number of wild condor chicks produced by the Arizona-Utah flock this season: here.

Andean condor chick video: here.

DDT Linked to Long-Term Decline of Insect-Eating Birds in North America, Through Analysis of Bird Droppings: here.

To control pest outbreaks, airplanes sprayed more than 6,280 tons of dichlorodiphenyltrichloroethane (DDT) onto forests in New Brunswick, Canada, between 1952 and 1968, according to Environment Canada. By 1970, growing awareness of the harmful effects of DDT on wildlife led to curtailed use of the insecticide in the area. However, researchers have now shown that DDT lingers in sediments from New Brunswick lakes, where it could alter zooplankton communities: here.

Some Canadian lakes still store DDT in their mud: here.

DDT Still Killing Birds in Michigan: here.

Earliest known animal tracks discovered?

This video is called Ediacaran Fauna Overview.

Another video from the USA which is no longer on the Internet, used to say about itself:

Rocks of the Proterozoic and Archean eras (The Precambrian) make up the inner gorge of the Grand Canyon on the Colorado Plateau. Proterozoic strata contains stromatolites, Chauria (small cap-like fossils) and Brooksella canyonensis, a fossil considered by some to be a fossil jellyfish and by others as a vendozoan (a group of puzzling late Precambrian firm impressions of what may be an extinct major category of life). The very hard rocks of the inner gorge belong to the Archean Era which in Arizona, may be younger in geologic time than nearer the continental nucleus where Archean rocks can be over three billion years old.

From World Science:

Found: earliest known animal tracks?

Oct. 5, 2008

Courtesy Ohio State University and World Science staff

Faint, fossilized tracks of an ancient aquat­ic crea­ture sug­gests an­i­mals walked us­ing legs at least 30 mil­lion years ear­li­er than had been thought, some sci­en­tists say. But they ad­mit the lack of a fos­sil of the crea­ture it­self will probably fos­ter a healthy skep­ti­cism, and that re­search­ers will need to look for ad­di­tion­al ev­i­dence.

The track­s—two par­al­lel rows of small dots, each about two mil­lime­ters wide—are dat­ed to some 570 mil­lion years ago, to a per­i­od called the Edi­a­ca­ran. That pre­ced­ed the Cam­bri­an per­i­od, when most ma­jor groups of an­i­mals evolved.

Sci­en­tists once thought that mainly mi­crobes and sim­ple mul­ti­cel­lu­lar an­i­mals ex­isted be­fore the Cam­bri­an, but that idea is chang­ing, said Lor­en Bab­cock, pro­fes­sor of earth sci­ences at Ohio State Uni­ver­s­ity.

He pro­nounced him­self “rea­sonably cer­tain” a centipede-like ar­thro­pod or a leg­ged worm made the tracks. An ar­thro­pod is an in­ver­te­brate hav­ing joint­ed limbs and a seg­mented bod­y—a group that in­cludes in­sects.

Soo-Yeun Ahn, a doc­tor­al stu­dent at Ohio State and a co-author of the re­search, pre­sented the find­ings at the Ge­o­log­i­cal So­ci­e­ty of Amer­i­ca meet­ing Sun­day in Hous­ton.

Bab­cock said he found the tracks while sur­vey­ing rocks in the moun­tains near Gold­field, Ne­vada in 2000. “We came on an out­crop that looked like it crossed the Pre­cam­brian-Cam­bri­an bound­ary…. We just sat down and started flip­ping rocks over. We were there less than an hour when I saw it.”

The crea­ture must have stepped lightly on­to the soft seabed, be­cause its legs pressed only shal­low pin­points in it, Bab­cock said. But when he flipped over the rock bear­ing the lit­tle pits, the low-angle sun­light cast them in crisp shad­ow, he re­called. He could­n’t be sure of the crea­ture’s length or num­ber of legs, but he guessed it car­ried a centimeter-wide body on many spindly legs.

In 2002, oth­er re­search­ers re­ported a si­m­i­lar fos­sil trail from Can­a­da that dat­ed back to the mid­dle of the Cam­bri­an per­i­od, about 520 mil­lion years ago. Anoth­er set of tracks found in South Chi­na date back to 540 mil­lion years ago.

ScienceDaily (Feb. 3, 2010) — Trails found in rocks dating back 565 million years are thought to be the earliest evidence of animal locomotion ever found: here.

Found: The first ever animal trails: here.

Earth’s earliest creatures dragged themselves along like a sea anemone some 565 million years ago, newly found tracks suggest: here.

Ediacaran Siberian fossils: here.

Early life on Earth may have developed more quickly than thought: here.

The Oldest Animal Fossils? Here.

Did life on Earth evolve twice? Listen to interview with Dr Adam Maloof: here.