The Devonian period is also known as the Age of Fishes. Here, we see the fish Dunkleosteus preying on eurypterids (sea scorpions), which in turn were feeding on the smaller trilobites. (Image credit: Aunt_Spray via Getty Images)
Depleting oxygen and rising hydrogen sulfide levels in the oceans may have been responsible for one of Earth’s most significant mass extinctions more than 350 million years ago, a new study finds. The changes were likely driven by rising sea levels and have some spooky parallels to conditions seen today.
Researchers studied samples of black shale from the Bakken Formation, a 200,000-square-mile (518,000 square kilometers) region partly laid down during the late Devonian that encompasses parts of North Dakota and Canada and is one of the largest contiguous deposits of natural gas and oil (opens in new tab) in the United States. The team found evidence that Earth experienced periods of oxygen depletion and hydrogen sulfide expansion, which likely contributed to the sweeping extinction events that ravaged Earth during the Devonian period (419.2 and 358.9 million years ago), or the “Age of Fishes.”
Hydrogen sulfide forms when algae decomposes on the ocean floor. The decomposition process also depletes the area of oxygen.
“There have been other mass extinctions presumably caused by expansions of hydrogen sulfide before, but no one has ever studied the effects of this kill mechanism so thoroughly during such a critical period of Earth’s history,” study co-author Alan Jay Kaufman (opens in new tab) , a geologist at the University of Maryland, said in a statement (opens in new tab) .
Related: Scientists just found a hidden mass extinction in Earth’s ancient past
During the Devonian period, sea life profilerated. Jawless fishes, known as placoderms, diversified widely throughout oceans that encircled the supercontinents Gondwana and Euramerica. Oceans were also full of trilobites and early ammonites, and extensive reefs fringed the continents. On land, Earth saw its first forests of ferns and early trees. By the mid-Devonian, Earth’s earliest known tetrapod Tiktaalik roseae had crawled out of the sea.
However, the Devonian period also saw some of the most significant extinctions in Earth’s history, including one of the five infamous ‘mass extinction’ events that led to the evolution of the flora and fauna we know today. Placoderms, trilobites and early ammonites disappeared, while cartilaginous fish-like sharks and rays proliferated.
To better the Devonian extinctions, the research team analyzed more than 100 core samples drilled from black shale deposits in the Bakken Formation. This organic-rich sediment accumulated near the end of the Devonian period, recording the environment within its chemical makeup.
The team found evidence of “anoxic events,” where waters were completely depleted of oxygen, they reported in the study, published March 8 in the journal Nature (opens in new tab) .
These sharp drops “are likely linked to a series of rapid rises in sea level” due to the melting of South Pole ice sheets during the preceding Silurian period (443.8 million to 419 million years ago), Kaufman said in the statement. related stories–After the ‘Great Dying,’ life on Earth took millions of years to recover. Now, scientists know why.
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Simultaneously, plants transformed rocky land into soil, which would have released nutrients to flow into those rising oceans. The influx of nutrients into the oceans would have triggered massive algal blooms, which died, decomposed and soaked up oxygen. As they decomposed, the dead algae released hydrogen sulfide, increasing levels of the toxic chemical.
The oxygen-depleted seas were too much for Devonian marine life. Researchers estimate that 75% of all life went extinct by the end of the Devonian.
The Devonian mass extinction is a warning for today, the study authors wrote. Oxygen-depleted dead zones emerge in oceans every year, in places like the Gulf of Mexico and the Baltic Sea (opens in new tab) . Intensive fertilizer use, plus sewage runoff, boost the ocean’s nutrient levels and encourage massive algal blooms. And as the globe warms and sea levels rise, the oceans won’t circulate oxygen as well, Kaufman said in the statement.
Past mass extinctions can help scientists understand the consequences of our actions today. Although the reasons for sea level rise and nutrient influx in the Devonian are different from today, they could lead to the same result — a massive loss of life in our planet’s oceans, the researchers argue.
Tennessee‘s Nico Iamaleava has been cleared medically to play Saturday against Georgia and is set to return as the Vols’ starting quarterback, sources told ESPN.
Iamaleava, a redshirt freshman, missed the second half of the 33-14 win over Mississippi State last week after suffering a blow to the head. He was listed as questionable earlier this week on the SEC availability report but has been removed in the latest report.
Iamaleava practiced this week, including team periods, and there was optimism among the staff that he was trending in the right direction and would be able to play. But the final call was made by medical personnel. Iamaleava was examined by doctors for what sources told ESPN were concussion-like symptoms after leaving the Mississippi State game. He did not return to the sideline for the second half.
Tennessee coach Josh Heupel said on Monday that he felt like Iamaleava would be in “great shape for Saturday” and noted that Iamaleava was with the team earlier Monday morning for meetings and team activities. The Vols’ first full-scale practice was Tuesday.
Iamaleava was having his most productive outing against an SEC team this season before leaving the game against Mississippi State. He completed 8 of 13 passes for 174 yards, no interceptions and a pair of touchdowns as Tennessee built a 20-7 halftime lead. In Iamaleava’s previous five SEC games, he had accounted for three touchdowns and turned it over five times. He was also sacked 15 times in those five games.
Redshirt senior Gaston Moore filled in for Iamaleava in the second half last week and finished 5-of-8 for 38 yards with no touchdowns or interceptions.
Getting Iamaleava back for the Georgia game is big news for Tennessee, which is right in the middle of the SEC championship race and College Football Playoff picture.
Receiver Dont’e Thornton (hand) has also been given the green light to play for Tennessee after earlier being listed as questionable.
Week 12 is here as we take a look at an SEC matchup that has College Football Playoff implications, learn about three of the nation’s top passers who all played under the same coach and see what’s going on in the Big 12.
No. 7 Tennessee will visit Sanford Stadium as it takes on conference opponent No. 12 Georgia on Saturday night. With so much at stake, what can each team improve on ahead of this SEC showdown?
The Big 12 has six teams in the hunt for a spot in the conference title game. With the final CFP rankings coming out in less than a month, what scenario looks most realistic for the conference in terms of how many of its teams could make the 12-team field?
Our college football experts preview big games and storylines ahead of the Week 12 slate.
It has been a historic (and dominant) season for Tennessee’s defense, which has yet to give up more than 19 points in any of its nine games. Against SEC competition, the Volunteers lead the conference in scoring defense, giving up 16.7 points per game, and also lead the way in third-down defense and red zone defense. In other words, they’ve given up very little of anything on defense and are buoyed by a line that’s both talented and deep. Tennessee plays a ton of players up front and has been especially good at forcing key turnovers. In 23 trips inside its own 20-yard line, the Vols have forced six turnovers.
The reality is that Tennessee has played to its defense for much of this season out of necessity. The offense has lacked consistency and struggled to generate explosive plays, particularly in the passing game. It’s not all on redshirt freshman quarterback Nico Iamaleava, either. Iamaleava has thrown only five touchdown passes in six SEC games, and the Vols are tied for 10th with an average of 7.5 yards per completion. Iamaleava, who sustained a head injury in a win over Mississippi State last week, has been the victim of poor pass protection at times, and his receivers have dropped some costly passes. Iamaleava has also been shaky when it comes to overthrowing receivers and occasionally holding onto the ball too long.
The bright spot on offense for Tennessee has been running back Dylan Sampson, who has a school-record 20 rushing touchdowns. He has been a constant for the Vols on offense and has an SEC-leading 772 rushing yards and 11 touchdowns in conference play. As good as he has been, the Vols are probably going to need more from their passing game to win in Athens. — Chris Low
The Bulldogs didn’t do much of anything well in last week’s 28-10 loss at Ole Miss, which was the first time in a long time that Kirby Smart’s team was manhandled on the lines of scrimmage.
The good news for Georgia: It’s heading home to Sanford Stadium for the first time in more than a month. Georgia hasn’t dropped back-to-back games in the regular season since 2016, Smart’s first season, and it has bounced back after each of its past eight losses. The Bulldogs have won seven of their past eight games against the Volunteers.
For all of quarterback Carson Beck‘s turnovers, Georgia’s problems on offense probably start up front. The offensive line hasn’t done a good job of protecting him, and the Bulldogs’ lack of a potent running game has prevented them from effectively utilizing play-action passes. Their banged-up offensive line is going to face another formidable defensive front Saturday. Georgia has 27 dropped passes, fourth most in the FBS, according to TruMedia, so its receivers need to become more reliable as well. — Mark Schlabach
The coach behind three of college football’s top passers
North Texas coach Eric Morris coached Ward at Incarnate Word and Washington State, recruited Mateer to the Cougars and signed Morris out of the transfer portal this offseason. All three hailed from Texas and are putting up big numbers this season. Morris, a Mike Leach disciple, knows what he’s looking for when it comes to QBs.
For each one, the journey was different. Ward was a zero-star recruit out of West Columbia, Texas, played in a wing-T offense and had no scholarship offers. But he showed up to Incarnate Word’s camp in 2019 and impressed with his quick release and accuracy. Morris saw appealing traits, too, in Ward’s multisport talents.
“He was such a good basketball player,” Morris said. “He was a bigger guy who could really handle the ball and move with ease. He had a twitch and quickness about him that was almost Mahomes-esque, where he’s not fast but you see him get out of the pocket and scramble and he’s nifty on his feet. He saw the floor great and shot the basketball great.
“It might be easier at an FCS school to take that risk, but it was something we were really confident in.”
Ward came in with extreme confidence, telling coaches he’d win the starting job over their returning all-conference player (and he did). He followed Morris to Pullman, Washington, out of loyalty to the coach who believed in him. Now he’s playing on a big stage, chasing a College Football Playoff bid and a Heisman Trophy with the No. 9 Hurricanes.
“It’s been fun to watch him flourish and get rewarded for being patient all these years,” Morris said.
When Morris left UIW to become Washington State’s offensive coordinator in 2022, he brought Ward but needed another QB. On his first recruiting trip in Texas, he stopped by to check out Mateer. The two-star recruit had a prolific senior season at Little Elm High School but was committed to Central Arkansas. Morris didn’t understand what FBS programs were missing and convinced Mateer to flip.
After two seasons behind Ward, Mateer has emerged as one of the top dual-threat QBs in college football with 2,332 passing yards, 805 rushing yards (excluding sacks) and 33 total TDs.
“I think the sky’s the limit,” Ward said. “He’s just so dang hard to tackle in the open field. Just a kid that loves ball and was under-recruited. The tide’s turned and he ends up being a big-time ballplayer.”
Chandler Morris was not an under-the-radar talent, but he’s having his best season yet at North Texas. He began his career at Oklahoma, won the starting job at TCU in 2022, sustained a knee injury in its season opener and then watched Max Duggan lead the Horned Frogs to the national title game.
Morris had a six-game stint as TCU’s starter last season before injuring the same knee. At UNT, he’s leading the nation’s No. 3 passing offense with 3,244 total yards and 30 TDs. Like Ward and Mateer, he processes information quickly, makes plays with his feet and throws outside the pocket with accuracy. If you ask Eric Morris, those traits are a must in today’s game. When paired with his version of Air Raid ball, you get big-time results.
“It’s been fun to see him get his swagger back,” Morris said.
Eric Morris points to Patrick Mahomes, Lamar Jackson and Jayden Daniels. The QBs thriving at the highest level are becoming unstoppable by creating plays out of the pocket. And so are his guys.
“Everybody obviously watches Cam and the magic he makes,” Morris said, “but I think all three of ’em can make plays when it’s not a perfect play call. There are a bunch of really good pure passers nowadays, but that’s what sets them all apart.” — Max Olson
What’s going on in the Big 12?
Two-thirds of the way through the Big 12 schedule, six teams are still in the hunt for a title-game appearance: BYU (6-0), Colorado (5-1), Arizona State, Iowa State, Kansas State and West Virginia, all of which are 4-2. There are too many variables to discuss all the scenarios, but the conference has a straightforward tiebreaker policy.
It’s possible to come up with scenarios in which the Big 12 could get two bids, one bid or shut out altogether.
For the Big 12 to get two bids, BYU probably would have to finish 12-0, then lose a close game in the championship to a two-loss team (Colorado, Iowa State or Kansas State). A 12-1 BYU team would get consideration, but it would become a question of how far it would fall and what else happens around the country.
The most likely scenario is the Big 12 will get one team in: whichever one wins the conference title game. If BYU wins out, it will have a bye, but if it slips up even once — or if another team wins the title — Boise State might be in position to get a first-round bye, assuming the Broncos win out.
The doomsday scenario in the Big 12 is if the conference champion has two or three losses and Army and Boise State win out. If that’s the case, there is a good possibility both of those schools would be ranked ahead of the Big 12 champion and the Big 12 would be left out. — Kyle Bonagura
Quotes of the Week
“They’re stubborn, man. They’re physical. He is an elite runner. The runs they run are sometimes nontraditional. They run some runs that other people don’t run because of the space in the box. He’s very patient. He hits small creases. He’s hard to tackle. How many touchdowns has he got in the SEC? Twenty-something? That’s crazy. In the SEC? The SEC is the hardest league in the world to run the ball in on because they’ve got the most size defensive lineman, and he continues to do it at a crazy pace to me.” — Kirby Smart on Volunteers tailback Dylan Sampson.
“I never try to take a step back. I try to take a step up. I’m always putting my head out the window. I’m trying to see around the corner, not trying to see straight ahead. It’s normalcy for everybody to see what’s in front of them. I’m trying to see around the corner. That’s the relationship I have with the Lord, to help me see around the corner so I can help navigate these young men as well as the women that’s attached to our program to a better way and a better life. So I don’t get caught up in the ‘You go, boys!’ or the ‘You ain’t nothing.’ You know, if I would’ve listened to you guys earlier, I’ve gotta listen to you now. So I might as well just put some headphones on and block you out. Notice I don’t have a sponsor for headphones, but that would’ve been a good placement for a sponsor.” — Deion Sanders when asked if he takes time to step back and appreciate the magnitude of Colorado’s turnaround.
“I hope anyone who has ambitions about playing in the National Football League, let’s see what you’ve got against Clemson. Let’s see you play your best game here. If you weren’t focused for Virginia, which I can’t imagine you weren’t — and I’m not saying anybody was not focused — but if they didn’t get your focus, I imagine Clemson will get your focus when you put the tape on.” — Pitt coach Pat Narduzzi on whether playing Clemson gets the attention of his players.
On today’s informative episode of Quick Charge, we’ve got Honda engineers Jason Hwang and Emilio Sanchez to talk us through some of the things that make the GM Ultium-based Honda Prologue EV feel like a real Honda, and why that matters.
Jason and Emilio talk about some of the choices they made to make the Honda Prologue and Acura ZDX feel different from its GM-branded cousins, and explain why this was much more than a case of badge-engineering. Give it a listen, then let us know what you think of the Prologue and ZDX in the comments.
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