It used to be thought that the ecosystems along California's coasts, which are centred on kelp forests, evolved about 14 million years ago but the discovery of 32-million-year-old fossil kelp means that estimate needs to be revised to a time before the modern marine mammals, urchins, birds and molluscs which now depend on these ecosystems had evolved.
It also means that kelp was probably an important food for a now-extinct hippopotamus-sized marine mammals, the desmostylians, probable relatives of manatees, sea cows and their terrestrial relatives, elephants.
The 14-million-year-old estimate assumed that all components of an ecosystem co-evolve, but this finding shows that the same foundation can lead to different ecosystems to evolve around them, consistent with new niches providing evolutionary opportunities in which mutation and variance can be selected for. In other words, the meaning of the genetic information is changed by the environment.
The discovery of the fossil kelp holdfasts and its significance is explained in a published paper In Proceeding of the National Academy of Science (PNAS) and in a news release from the University of California at Berkeley (UC Berkeley):
The unique underwater kelp forests that line the Pacific Coast support a varied ecosystem that was thought to have evolved along with the kelp over the past 14 million years.
But a new study shows that kelp flourished off the Northwest Coast more than 32 million years ago, long before the appearance of modern groups of marine mammals, sea urchins, birds and bivalves that today call the forests home.
The much greater age of these coastal kelp forests, which today are a rich ecosystem supporting otters, sea lions, seals, and many birds, fish and crustaceans, means that they likely were a main source of food for an ancient, now-extinct mammal called a desmostylian. The hippopotamus-sized grazer is thought to be related to today's sea cows, manatees and their terrestrial relatives, the elephants.
Evidence for the greater antiquity of kelp forests, reported this week in the journal Proceedings of the National Academy of Sciences, comes from newly discovered fossils of the kelp’s holdfast — the root-like part of the kelp that anchors it to rocks or rock-bound organisms on the seafloor. The stipe, or stem, attaches to the holdfast and supports the blades, which typically float in the water, thanks to air bladders.People initially said, 'We don't think the kelps were there before 14 million years ago because the organisms associated with the modern kelp forest were not there yet. Now, we show the kelps were there, it's just that all the organisms that you expect to be associated with them were not. Which is not that strange, because you first need the foundation for the whole system before everything else can show up.
Professor Cindy Looy, co-author
Professor of integrative biology
Department of Integrative Biology
Museum of Paleontology, and Herbarium, University of California, Berkeley, CA, USA
Looy's colleague, Steffen Kiel, dated these fossilized holdfasts, which still grasp clams and envelop barnacles and snails, to 32.1 million years ago, in the middle of the Cenozoic Era, which stretches from 66 million years ago to the present. The oldest previously known kelp fossil, consisting of one air bladder and a blade similar to that of today's bull kelp, dates from 14 million years ago and is in the collection of the University of California Museum of Paleontology (UCMP).
A fossilized holdfast (top) with the axis (ax) where the stem, or stipe, would have attached. Arrows indicate the lobe-like meristematic transition zone (mtz) that divides into branching, finger-like haptera. At bottom is an X-ray reconstruction of the same 32-million-year-old fossil kelp holdfast colored to show the base (orange), holdfast (yellow) and the bivalve shell to which it attached (blue).Dula Parkinson, Berkeley Lab Advanced Light Source, and Tony Huynh, UC BerkeleyAccording to Kiel and Looy, who is the senior author of the paper and UCMP curator of paleobotany, these early kelp forests were likely not as complex as the forests that evolved by about 14 million years ago. Fossils from the late Cenozoic along the Pacific Coast indicate an abundance of bivalves — clams, oysters and mussels — birds and sea mammals, including sirenians related to manatees and extinct, bear-like predecessors of the sea otter, called Kolponomos. Such diversity is not found in the fossil record from 32 million years ago.Our holdfasts provide good evidence for kelp being the food source for an enigmatic group of marine mammals, the desmostylia. This is the only order of Cenozoic mammals that actually went extinct during the Cenozoic. Kelp had long been suggested as a food source for these hippo-sized marine mammals, but actual evidence was lacking. Our holdfasts indicate that kelp is a likely candidate.
Another implication is that the fossil record has, once again, shown that the evolution of life — in this case, of kelp forests — was more complex than estimated from biological data alone. The fossil record shows that numerous animals appeared in, and disappeared from, kelp forests during the past 32 million years, and that the kelp forest ecosystems that we know today have only evolved during the past few million years.
Steffen Kiel, lead author
Senior curator
Department of Palaeobiology
Swedish Museum of Natural History, Stockholm, Sweden.
The value of fossil hunting amateurs
The fossils were discovered by James Goedert, an amateur fossil collector who has worked with Kiel in the past. When Goedert broke open four stone nodules he found along the beach near Jansen Creek on the Olympic Peninsula in Washington, he saw what looked like the holdfasts of kelp and other macroalgae common along the coast today.Kiel, who specializes in invertebrate evolution, agreed and subsequently dated the rocks based on the ratio of strontium isotopes. He also analyzed oxygen isotope levels in the bivalve shells to determine that the holdfasts lived in slightly warmer water than today, at the upper range of temperatures found in modern kelp forests.
The coastal area on the Olympic Peninsula of Washington where most of the fossilized holdfasts were collected by amateur paleontologist James Goedert.Steffen Kiel
Looy reached out to co-author Dula Parkinson, a staff scientist with the Advanced Light Source at Lawrence Berkeley National Laboratory, for help obtaining a 3D X-ray scan of one of the holdfast fossils using Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM). When she reviewed the detailed X-ray slices through the fossil, she was amazed to see a barnacle, a snail, a mussel and tiny, single-celled foraminifera hidden within the holdfast, in addition to the bivalve on which it sat.
Looy noted, however, that the diversity of invertebrates found within the 32-million-year-old fossilized holdfast was not as high as would be found inside a kelp holdfast today.
This timeline depicts the evolution of kelp forests and associated organisms along the Pacific Coast over the past 32 million years, along with water temperature variations. Black bars indicate members of the modern, complex kelp ecosystems — sea otters, abalone, sea urchins and, until recently, sea cows. The green bars indicate now-extinct members of early kelp beds, including desmostylians and penguin-like plotopterids.Credit: Steffan Kiel, Cindy Looy and Rosemary Romero
"The holdfasts are definitely not as rich as they would be if you would go to a kelp ecosystem right now," Looy said. "The diversifying of organisms living in these ecosystems hadn't started yet."
Kiel and Looy plan further studies of the fossils to see what they reveal about the evolution of the kelp ecosystem in the North Pacific and how that relates to changes in the ocean-climate system.
SignificanceOn display here is the in-built self-correcting nature of science, based on the intellectually honest position that when the facts or our understanding of the facts changes, we change our minds - something that is impossible for a religious fundamentalist like a creationist which is based on the intellectually bankrupt position that when the facts don't support us, we ignore the facts and continue to hold counter-factual opinions because our opinions trump reality.
Molecular and morphological studies suggest that kelps—large, marine brown algae—originated around the Eocene–Oligocene transition about 34 Mya. This paper documents kelp holdfasts from earliest Oligocene strata in Washington State, USA, that provide evidence for these age estimates and the morphology of early kelps. The fossils also highlight the preservational potential of brown algal holdfasts, which likely exceeds that of the soft blades that constitute the hitherto known fossil record of kelps. Reviewing the fossil record in light of the data supports the view that kelp evolution in the North Pacific was stepwise and enabled by climatic changes.
Abstract
Kelp forests are highly productive and economically important ecosystems worldwide, especially in the North Pacific Ocean. However, current hypotheses for their evolutionary origins are reliant on a scant fossil record. Here, we report fossil hapteral kelp holdfasts from western Washington State, USA, indicating that kelp has existed in the northeastern Pacific Ocean since the earliest Oligocene. This is consistent with the proposed North Pacific origin of kelp associated with global cooling around the Eocene–Oligocene transition. These fossils also support the hypotheses that a hapteral holdfast, rather than a discoid holdfast, is the ancestral state in complex kelps and suggest that early kelps likely had a flexible rather than a stiff stipe. Early kelps were possibly grazed upon by mammals like desmostylians, but fossil evidence of the complex ecological interactions known from extant kelp forests is lacking. The fossil record further indicates that the present-day, multi-story kelp forest had developed at latest after the mid-Miocene climate optimum. In summary, the fossils signify a stepwise evolution of the kelp ecosystem in the North Pacific, likely enabled by changes in the ocean-climate system.
Kiel, Steffen; Goedert, James L.; Huynh, Tony L.; Krings, Michael; Parkinson, Dula; Romero, Rosemary; Looy, Cindy V.
Early Oligocene kelp holdfasts and stepwise evolution of the kelp ecosystem in the North Pacific
Proceedings of the National Academy of Sciences, 121(4) e2317054121. DOI: 10.1073/pnas.2317054121
© 2024 PNAS.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
Also on display here are two of those facts creationists need to ignore, to retain their counter0factual opinion - that there were thriving ecosystems based on kelp forests 32 million years before 'Creation Week', and the scientists show no evidence of adopting unintelligently design creationism as their preferred model for interpreting the evidence and show no doubt that the TOE is the perfect tool, intelligently designed for the job.
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