German scientists have found an unusually long trail of footprints from a 30-ton dinosaur in an abandoned quarry in Lower Saxony, and think they could be around 145 million years old.

"It's very unusual how long the trail is and what great condition it's in," excavation leader Benjamin Englich said at the site, referring to 90 uninterrupted footprints stretching over 50 meters. Their diameter measures 1.2 meters.

Englich and his team found the impressions in the central German region while excavating at the quarry in the town of Rehburg-Loccum near Hanover on Wednesday.

Englich said the elephant-like tracks were stomped into the ground sometime between 135 and 145 million years ago by a sauropod — a class of heavy dinosaurs with long necks and tails.

"We don't have a complete skeleton for a dinosaur this big from this time period," said Englich. "That means it's a species we haven't seen before from this era."

The prehistoric prints are not only big, said Englich, but also unusually deep. The impressions sink more than 40 centimeters into the ground, suggesting they were made by a creature that weighed up to 30 tons.

Experts hope the trail could help shed light on conditions in the Cretaceous Period, the mysterious era that ended 65 million years ago with the mass extinction of dinosaurs.

The biggest dinosaur prints ever found, measuring up to 2 meters in diamater, were discovered by amateur diggers in the French Jura region in 2009.